warfare, violent conflict between armed enemies. In modern times warfare has usually been conducted by the armed forces (e.g., army, navy, and air force) of a nation or other politically organized group. The way in which war is carried out is governed by the principles of strategy and tactics, by the type of weapons employed (see articles on individual weapons), and by the type of communication and transportation facilities available. Thus, throughout history the methods of warfare have changed. See air forces; amphibious warfare; chemical warfare; biological warfare; fortification; mechanized warfare; trench warfare; guerrilla warfare; siege.

trench warfare. Although trenches were used in ancient and medieval warfare, in the American Civil War, and in the Russo-Japanese War (1904-5), they did not become important until World War I. The introduction of rapid-firing small arms and artillery made the infantry charges of earlier wars virtually impossible, and the war became immobile, with the contenders digging thousands of miles of opposing trenches fronted by barbed wire. To break the stalemate various methods and new weapons were tried; tremendous artillery barrages sought to devastate the enemy and blow a gap in his trenches; trench mortars, hand grenades, poison gas, and tanks were used. It nevertheless remained a war of attrition, with artillery duels and infantry attacks behind creeping artillery barrages. The idea of an uninterrupted line defense held the imagination of the French and German general staffs between the two world wars, and they built lines of field fortifications known as the Maginot Line and the Siegfried Line. The advent of mechanized warfare made it possible to circumvent such defenses, and World War II was a war of movement. However, in the last stages of the Korean war both sides established fortified positions across the Korean peninsula, and a stalemated situation similar to that of World War I came into play.

mechanized warfare, employment of modern mobile attack and defense tactics that depend upon machines, more particularly upon vehicles powered by gasoline and diesel engines. Central to the waging of mechanized warfare are the tank and armored vehicle, with support and supply from motorized columns and aircraft. Automobiles were of great use in World War I. The tank was introduced at Cambrai in 1917, and its use was enthusiastically endorsed by the British general J. F. C. Fuller. The need for air protection and support was emphasized by the American general William Mitchell. Although the basic essentials of mechanized warfare were thus established early, it was not until Germany attacked Poland at the start of World War II that its full potentials were revealed. German armored (Panzer) divisions, supported by aircraft, proved their worth in Poland and France and later won spectacular successes in the Balkans, the Soviet Union, and Africa. Outstanding among the German proponents of this type of warfare were Heinz Guderian and Erwin Rommel. The German triumphs brought recognition to other advocates of mechanized warfare, e.g., Liddell Hart and Charles de Gaulle. The British and American armies also created armored divisions, and they developed weapons for defense against mechanized attack, e.g., the antitank gun and the tank destroyer. The Germans used their mechanized forces for deep penetrations into enemy territory but were ultimately beaten by superior use of artillery and aircraft as shown by the Allies in the battle of El Alamein and other engagements. The Allies themselves developed the use of mechanized warfare with brilliant success, as in the overrunning of Western Europe (1944-45) by Allied forces under such leaders as Gen. George S. Patton. The Israeli desert offensives of 1956 and 1967 involved close coordination of motorized infantry units with air and parachute forces; in the Vietnam War helicopters helped to increase the mobility of troops and equipment. Mechanized warfare has been augmented by technological developments to such an extent that the concept has become largely superfluous.

guerrilla warfare [Span.,=little war], fighting by groups of irregular troops (guerrillas) within areas occupied by the enemy. When guerrillas obey the laws of conventional warfare they are entitled, if captured, to be treated as ordinary prisoners of war; however, they are often executed by their captors. The tactics of guerrilla warfare stress deception and ambush, as opposed to mass confrontation, and succeed best in an irregular, rugged, terrain and with a sympathetic populace, whom guerrillas often seek to win over by propaganda, reform, and terrorism. Guerrilla warfare has played a significant role in modern history, especially when waged by Communist liberation movements in Southeast Asia and elsewhere.

History

In the American Revolution and the Nineteenth Century

Large-scale guerrilla fighting accompanied the American Revolution, and the development of guerrilla tactics under such partisan leaders as Francis Marion, Andrew Pickens, and Thomas Sumter has been called the great contribution of the American Revolution to the development of warfare. The term guerrilla itself was coined during the Peninsular War (1808-14), when Spanish partisans, under such leaders as Francisco Mina, proved unconquerable even by the armies of Napoleon I. From Spain the use of the term spread to Latin America and then to the United States.

During the U.S. Civil War, William C. Quantrill, who operated in Missouri and Kansas, was the most notorious of the Confederate guerrilla leaders, but John S. Mosby, in Virginia, was undoubtedly the most effective. During the Franco-Prussian War (1870-71) the Germans suffered so much from French partisans, or francs-tireurs, that Field Marshall von Moltke ordered the shooting of all prisoners not fully uniformed and led by regular officers. In the Philippines after the Spanish-American War, the U.S. Army conducted a long campaign against Filipino guerrillas, such as Emilio Aguinaldo, and Moro bands. There has been frequent guerrilla warfare in Latin America. Notable among early 20th-century Latin American guerrillas are Francisco (Pancho) Villa, Emiliano Zapata, and Augusto C. Sandino.

World War I to World War II

In World War I the most spectacular theater of guerrilla operations was the Arabian peninsula, where, under the leadership of T. E. Lawrence and Faisal al-Husayn (later Faisal I), various Arab guerrilla bands fought superior Turkish forces. In the late 1920s and 30s the Chinese Communists under the leadership of Mao Zedong, perhaps the world's leading theorist of modern guerrilla warfare, conducted a large-scale guerrilla war, along with mobile and positional warfare, against both the Kuomintang and the Japanese in N China. Mao saw the People's War, as he called it, progressing from minor skirmishing to a conventional conflict as he led the Communists to victory.

Guerrilla tactics, aided by the development of the long-range portable radio and the use of aircraft as a means of supply, reached new heights in World War II. The Germans failed to establish a complete hold on Yugoslavia because of the guerrilla resistance, which was led by the Communist partisan leader Tito and supplied in part by Allied airdrops. In the Soviet Union guerrilla warfare was included in instruction at the military academy; in the field it was so brilliantly organized that it constituted a continual threat to the German rear and contributed greatly to the German disaster on the Eastern Front.

In Western Europe the Allies organized guerrilla forces in France, Norway, Denmark, Holland, Belgium, Italy, and Greece. These forces (known collectively as the "underground" and, in France, as the maquis) were supplied by Allied airdrops and coordinated from London by radio. The resistance forces in Western Europe, led mainly by British- and American-trained officers, conducted not only guerrilla operations but also industrial sabotage, espionage, propaganda campaigns, and the organization of escape routes for Allied prisoners of war.

By the end of World War II resistance forces had played a major role in the defeat of Germany. Throughout the war the United States and Britain also carried on guerrilla warfare in the Philippines and Southeast Asia, and in China large-scale guerrilla operations were conducted against the Japanese by both Communists and Nationalists.

Since World War II

Since World War II guerrilla warfare has been employed by nationalist groups to overthrow colonialism, by dissidents to launch civil wars, and by Communist and Western powers in the cold war. There have been dozens of such conflicts.

Just after World War II large-scale guerrilla warfare broke out in Indochina between the French and the Communist Viet Minh, led by Ho Chi Minh and Vo Nguyen Giap. After the French defeat at Dienbienphu (1945), France withdrew from the conflict; but the 1954 Geneva Conference brought no permanent peace, and Communist guerrilla activity continued in Laos, Cambodia, and South Vietnam. In the subsequent Vietnam War the United States fought in support of the South Vietnamese government against local guerrillas (Viet Cong) aided by North Vietnamese troops. In Cambodia, the Khmer Rouge waged guerrilla warfare to win control of the nation and, after being ousted by the Vietnamese army, again resorted to it until the group's disintegration (1999).

In Algeria guerrilla warfare against the French was begun by the nationalists in 1954 and conducted with ever-increasing violence until Algeria won its independence in 1961. Greek nationalists in Cyprus carried on guerrilla warfare against the British from 1954 until that country gained independence in 1959. Fidel Castro and Ernesto (Che) Guevara in 1956 launched a guerrilla war in Cuba against the government of Fulgencio Batista; in 1959, Batista fled the country and Castro assumed control. This success gave encouragement to rebel guerrilla bands throughout Latin America. In 1967, Guevara was killed by the Bolivian army while leading such a rebel band in the jungles of Bolivia.

In the late 1960s, Palestinian Arab guerrillas intensified their activities against the state of Israel. In 1971, after a full-scale war with the Jordanian army, they were ousted from their bases in Jordan. However, the Palestine Liberation Organization (PLO) and other groups continued their raids on Israel from other Arab countries. After the PLO was forced to leave Lebanon (1982, 1991) its fighters were again dispersed, but it continued to mount attacks until peace negotiations in the early 1990s.

The United States has sponsored guerrillas, most notably anti-Castro Cuban forces and Nicaraguan contras. Modern "urban guerrilla" activities such as hijacking and kidnapping are frequently inspired by ideology rather than patriotism and are often tinged with elements of terrorism. The Irish Republican Army (late 1960s to mid-1990s) and Peru's Shining Path engaged in both attacks on government forces and various forms of terrorism. In the 1990s many nations experienced some degree of ongoing societal disruption due to persistent guerrilla warfare, among them Algeria, Burundi, Cambodia, Colombia, Rwanda, Sierra Leone, and Turkey (in Kurdish areas).

germ warfare: see biological warfare.

chemical warfare, employment in war of incendiaries, poison gases, and other chemical substances. Ancient armies attacking or defending fortified cities threw burning oil and fireballs. A primitive type of flamethrower was employed as early as the 5th cent. B.C.; modern types are still in use. In the Middle Ages, before the introduction of gunpowder, a flammable composition known as Greek fire was used. Smoke from burning straw or other material was employed in early times, but its effectiveness is uncertain.

Poison gas was first used during World War I, when the Germans released (Apr., 1915) chlorine gas against the Allies. The Germans also introduced mustard gas later in the war. Afterward, the major powers continued to stockpile gases for possible future use and several actually used it: the British in Afghanistan, the French and Spanish in Africa, the Italians in Ethiopia, and the Japanese in China. Lethal gases were not employed in combat during World War II, but the Germans did use gases for mass murder during the Holocaust. The Germans also invented and stockpiled the first nerve gas. It is odorless and colorless and attacks the body muscles, including the involuntary muscles. It is the most lethal and insidious weapon of chemical warfare. Since World War II, chemical weapons are known to have been used by Egypt in Yemen (during the 1962-67 civil war) and by Iraq against Iran during the Iran-Traq War and against Kurdish rebels.

Besides lethal gases, which attack the skin, blood, nervous, or respiratory system and require hospitalization of the victim, there are also nonlethal incapacitating agents, which, like tear gas, cause temporary physical disability. Such agents have often been employed in riot control, espionage, and warfare. Various forms of herbicides and defoliants are also used to destroy crops or vegetation, as Agent Orange was used by the United States during the Vietnam War.

The potential effectiveness of chemical warfare is increasing with improved methods of dissemination, such as artillery shells, grenades, missiles, and aircraft and submarine spray guns. Some protection against chemical weapons is possible using suits, sealed vehicles, and shelters. Such countermeasures usually protect against nuclear fallout and biological warfare as well. Lethal chemical weapons are held by many nations and they continue to be used. The danger of the proliferation of chemical and biological weapons remains despite arms control because they are relatively easy to manufacture and deploy.

Efforts to control chemical and biological weapons began in the late 19th cent. The Geneva Protocol of 1925, which went into force in 1928, condemned the use of chemical weapons but did not ban the development and stockpiling of chemical weapons. The United States did not ratify the protocol until 1974. In 1990, with the end of the cold war, the United States and the Soviet Union agreed to cut their arsenals by 80% in an effort to create a climate of change that would discourage smaller nations from stockpiling and using such lethal weapons. In 1993 a international treaty banning the production, stockpiling (both by 2007), and use of chemical weapons and calling for the establishment of an independent organization to verify compliance was adopted. The agreement, which became effective in 1997, has been signed and ratified by 160 nations. The treaty is enforced by the Organization for the Prohibition of Chemical Weapons, which is based in The Hague. The alleged Iraqi retention, after the Persian Gulf War cease-fire, of chemical weapons and other weapons of mass destruction was the main pretext for the 2003 U.S.-British invasion of Iraq.

biological warfare, employment in war of microorganisms to injure or destroy people, animals, or crops; also called germ or bacteriological warfare. Limited attempts have been made in the past to spread disease among the enemy; e.g., military leaders in the French and Indian Wars tried to spread smallpox among the Native Americans. Biological warfare has scarcely been used in modern times and was prohibited by the 1925 Geneva Convention. However, many nations in the 20th cent. have conducted research to develop suitable military microorganisms, including strains of smallpox, anthrax, plague, and some nonlethal agents. Such microorganisms can be delivered by animals (especially rodents or insects) or by aerosol packages, built into artillery shells or the warheads of ground-to-ground or air-to-ground missiles and released into the atmosphere to infect by inhalation.

In 1972 the United States and the Soviet Union adopted an agreement, endorsed by the UN General Assembly and now ratified by more than 140 nations, to destroy existing stockpiles of biological weapons and refrain from developing or stockpiling new biological weapons. The treaty does allow research for defensive purposes, such as to develop antidotes to biological weapons. After the fall of the Soviet Union, however, it was disclosed that the Soviets had secretly increased research and production of a wide variety of deadly biological agents. Although Russian president Boris Yeltsin publicly ordered (1992) the abandonment of germ warfare, some expressed suspicion about the continued production of biological weapons in post-cold war Russia.

With the rise of extremist groups and the disintegration of the established international political order in the late 20th cent., biological weapons again began to be perceived as a serious threat. In the 1990s, after the Persian Gulf War, five hidden germ-warfare laboratories and stockpiles of anthrax, botulism, and gas gangrene bacteria were discovered in Iraq. In addition to Iraq and Russia, North Korea, Iran, Egypt, Israel, China, and other nations are suspected of various violations of the 1972 agreement.

In 2001, shortly after the terrorist attacks on the World Trade Center and Pentagon, anthrax was sent through the mail in bioterrorist attacks against several locations in the United States. There was, however, no clear connection between the two terror attacks. In an attempt to develop a warning system for a bioterror attack, the Environmental Protection Agency's air quality monitoring system was adapted (2003) to permit detection of an outdoor release of smallpox and other pathogens. Such a system, however, would not have detected the narrowly focused indoor anthrax attacks of 2001.

See also chemical warfare.

amphibious warfare, employment of a combination of land and sea forces to take or defend a military objective. The general strategy is very ancient and was extensively employed by the Greeks, e.g., in the Athenian attack on Sicily in 415 B.C. The term is, however, of modern coinage. It is sometimes applied to the joint operations of the Allied army and naval forces in the disastrous Gallipoli campaign (1915) of World War I. Amphibious warfare was widely employed in World War II. When the Japanese entered the war on a large scale in Dec., 1941, they used combined air, land, and naval operations to capture strategic islands such as the Philippines, Java, and Sumatra. However, the Japanese landings, like the Allied landing in N Africa (Nov., 1942), encountered little opposition and did not offer a true illustration of the problems of amphibious warfare. The problem faced by the Allies in the reconquest of Europe and the Pacific islands was how to land their forces on a heavily defended coast line. It was solved by the construction of special vessels called landing craft that were seaworthy and yet capable of allowing tanks and infantry to emerge without difficulty into shallow water for landing. The typical Allied amphibious operation consisted of heavy and continued air and naval bombardment of the enemy defenses, followed by a landing of troops with complete equipment from landing craft; the landing forces were supported in the early stages by naval guns until land artillery could come into action. By use of this method the Allies were able to invade heavily defended Pacific islands such as Tarawa (1943), Saipan (1944), Iwo Jima (1945), and Okinawa (1945). In Europe the Allies made landings on Sicily (1943) and Italy (1943-44), but the most spectacular example of amphibious warfare was the invasion of Normandy by the Allies from England on June 6, 1944 (see Normandy campaign). That action was a prime example of combined movements of naval craft, land forces, and aircraft (used for offense, protection of other forces, and transport). The U.S. invasion of Incheon (1950) during the Korean War and the British and French invasion of Egypt during the Sinai crisis (1957) utilized the same basic tactics. Amphibious landings later occurred in Vietnam War and in the British retaking (1982) of the Falkland Islands. Modern amphibious assault ships use helicopters and VTOL airplanes to mount and support amphibious attacks.

Any violation of the laws of war, as laid down by international customary law and certain international treaties. At the end of World War II, the part of the London Agreement signed by the U.S., Britain, the Soviet Union, and France established three categories of war crime: conventional war crimes (including murder, ill treatment, or deportation of the civilian population of occupied territories), crimes against peace, and crimes against humanity (political, racial, or religious persecution against any civilian population). The charter also provided for an international military tribunal to try major Axis war criminals. It further stated that a defendant's position as head of state would not free him from accountability, nor would having acted on orders or out of military necessity. German and Japanese war criminals were tried before Allied tribunals in Nürnberg and Tokyo in 1945–46 and 1946–48, respectively, and in the 1990s tribunals were created for the prosecution of war crimes committed in Rwanda and the territory of the former Yugoslavia. Seealso Geneva Convention; genocide; Hague Convention; Nürnberg trial.

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State of conflict, generally armed, between two or more entities. It is characterized by intentional violence on the part of large bodies of individuals organized and trained for that purpose. On the national level, some wars are fought internally between rival political factions (civil war); others are fought against an external enemy. Wars have been fought in the name of religion, in self-defense, to acquire territory or resources, and to further the political aims of the aggressor state's leadership.

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Military conflict in which the contenders mobilize all of their civilian and military resources in order to obtain a complete victory. It is distinguished from the partial commitment of lives and resources in limited war. The modern concept of total war is traced to Carl von Clausewitz, who stressed the importance of crushing the adversary's forces in battle and described wars as tending constantly to escalate in violence toward a theoretical absolute. The classic 20th-century work is Erich Ludendorff's The Total War (1935). World Wars I and II are usually regarded as total wars. After World War II, especially during the Cold War, the prospect of an all-out nuclear war made the major powers reluctant to engage in full-scale international warfare or allow their client states to do so.

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Set of conditions under which a resort to war is morally legitimate (jus ad bellum); also, rules for the moral conduct of war (jus in bello). Among the proposed conditions for the just resort to war are that the cause be just (e.g., self-defense against an attack or the threat of imminent attack), that the authority undertaking the war be competent, that all peaceful alternatives be exhausted, and that there be a reasonable hope of success. Two of the most important conditions for the just conduct of war are that the force used be “proportional” to the just cause the war is supposed to serve (in the sense that the evil created by the war must not outweigh the good represented by the just cause) and that military personnel be discriminated from innocents (noncombatant civilians), who may not be killed. The concept of just war was developed in the early Christian church; it was discussed by St. Augustine in the 4th century and was still accepted by Hugo Grotius in the 17th century. Interest in the concept thereafter declined, though it was revived in the 20th century in connection with the development of nuclear weapons (the use of which, according to some, would violate the conditions of proportionality and discrimination) and the advent of “humanitarian intervention” to put an end to acts of genocide and other crimes committed within the borders of a single state.

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Any war fought by divine command or for a primarily religious purpose. The concept is found in the Bible (e.g., the Book of Joshua) and has played a role in many religions. The Crusades are Europe's best-known example. In Islam, the concept is called jihad. Wars in which religion plays a secondary or exacerbating role are not generally called holy wars.

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or Second World War

(1939–45) International conflict principally between the Axis Powers—Germany, Italy, and Japan—and the Allied Powers—France, Britain, the U.S., the Soviet Union, and China. Political and economic instability in Germany, combined with bitterness over its defeat in World War I and the harsh conditions of the Treaty of Versailles, allowed Adolf Hitler and the Nazi Party to rise to power. In the mid-1930s Hitler began secretly to rearm Germany, in violation of the treaty. He signed alliances with Italy and Japan to oppose the Soviet Union and intervened in the Spanish Civil War in the name of anticommunism. Capitalizing on the reluctance of other European powers to oppose him by force, he sent troops to occupy Austria in 1938 (see Anschluss) and to annex Czechoslovakia in 1939. After signing the German-Soviet Nonaggression Pact, Germany invaded Poland on Sept. 1, 1939. Two days later France and Britain declared war on Germany. Poland's defeat was followed by a period of military inactivity on the Western Front (see Phony War). At sea Germany conducted a damaging submarine campaign by U-boat against merchant shipping bound for Britain. By early 1940 the Soviet Union had divided Poland with Germany, occupied the Baltic states, and subdued Finland in the Russo-Finnish War. In April 1940 Germany overwhelmed Denmark and began its conquest of Norway. In May German forces swept through The Netherlands and Belgium on their blitzkrieg invasion of France, forcing it to capitulate in June and establish the Vichy France regime. Germany then launched massive bombing raids on Britain in preparation for a cross-Channel invasion, but, after losing the Battle of Britain, Hitler postponed the invasion indefinitely. By early 1941 Hungary, Romania, and Bulgaria had joined the Axis, and German troops quickly overran Yugoslavia and Greece in April. In June Hitler abandoned his pact with the Soviet Union and launched a massive surprise invasion of Russia, reaching the outskirts of Moscow before Soviet counterattacks and winter weather halted the advance. In East Asia Japan expanded its war with China and seized European colonial holdings. In December 1941 Japan attacked U.S. bases at Pearl Harbor and in the Philippines. The U.S. declared war on Japan, and the war became truly global when the other Axis Powers declared war on the U.S. Japan quickly invaded and occupied most of Southeast Asia, Burma, the Netherlands East Indies, and many Pacific islands. After the crucial U.S. naval victory at the Battle of Midway (1942), U.S. forces began to advance up the chains of islands toward Japan. In the North Africa Campaigns the British and Americans defeated Italian and German forces by 1943. The Allies then invaded Sicily and Italy, forcing the overthrow of the fascist government in July 1943, though fighting against the Germans continued in Italy until 1945. In the Soviet Union the Battle of Stalingrad (1943) marked the end of the German advance, and Soviet reinforcements in great numbers gradually pushed the German armies back. The massive Allied invasion of western Europe began with the Normandy Campaign in western France (1944), and the Allies' steady advance ended in the occupation of Germany in 1945. After Soviet troops pushed German forces out of the Soviet Union, they advanced into Poland, Czechoslovakia, Hungary, and Romania and had occupied the eastern third of Germany by the time the surrender of Germany was signed on May 8, 1945. In the Pacific an Allied invasion of the Philippines (1944) was followed by the successful Battle of Leyte Gulf and the costly Battles of Iwo Jima and Okinawa (1945). Atomic bombs were dropped on Hiroshima and Nagasaki in August 1945, and Japan's formal surrender on September 2 ended the war. Estimates of total military and civilian casualties varied from 35 million to 60 million killed, including about 6 million Jews who died in the Holocaust. Millions more civilians were wounded and made homeless throughout Europe and East Asia. Seealso Anti-Comintern Pact; Atlantic Charter; Battles of El Alamein, the Atlantic, the Bulge, Guadalcanal, and the Philippine Sea; Casablanca, Potsdam, Tehran, and Yalta conferences; Dunkirk Evacuation; lend-lease; Munich agreement; Nürnberg Trials; Siege of Leningrad; Sino-Japanese Wars; Omar Bradley, Winston Churchill, Dwight D. Eisenhower, Douglas MacArthur, Bernard Law Montgomery, Benito Mussolini, George Patton, Erwin Rommel, Franklin Roosevelt, Joseph Stalin, Yamamoto Isoroku, Georgy K. Zhukov.

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or First World War

(1914–18) International conflict between the Central Powers—Germany, Austria-Hungary, and Turkey—and the Allied Powers—mainly France, Britain, Russia, Italy, Japan, and (from 1917) the U.S. After a Serbian nationalist assassinated Archduke Francis Ferdinand of Austria in June 1914, a chain of threats and mobilizations resulted in a general war between the antagonists by mid-August. Prepared to fight a war on two fronts, based on the Schlieffen Plan, Germany first swept through neutral Belgium and invaded France. After the First Battle of the Marne (1914), the Allied defensive lines were stabilized in France, and a war of attrition began. Fought from lines of trenches and supported by modern artillery and machine guns, infantry assaults gained little ground and were enormously costly in human life, especially at the Battles of Verdun and the Somme (1916). On the Eastern Front, Russian forces initially drove deep into East Prussia and German Poland (1914) but were stopped by German and Austrian forces at the Battle of Tannenberg and forced back into Russia (1915). After several offensives, the Russian army failed to break through the German defensive lines. Russia's poor performance and enormous losses caused widespread domestic discontent that led to the Russian Revolution of 1917. Other fronts in the war included the Dardanelles Campaign, in which British and Dominion forces were unsuccessful against Turkey; the Caucasus and Iran (Persia), where Russia fought Turkey; Mesopotamia and Egypt, where British forces fought the Turks; and northern Italy, where Italian and Austrian troops fought the costly Battles of the Isonzo. At sea, the German and British fleets fought the inconclusive Battle of Jutland, and Germany's use of the submarine against neutral shipping eventually brought the U.S. into the war in 1917. Though Russia's armistice with Germany in December 1917 released German troops to fight on the Western Front, the Allies were reinforced by U.S. troops in early 1918. Germany's unsuccessful offensive in the Second Battle of the Marne was countered by the Allies' steady advance, which recovered most of France and Belgium by October 1918 and led to the November Armistice. Total casualties were estimated at 10 million dead, 21 million wounded, and 7.7 million missing or imprisoned. Seealso Battles of Caporetto and Ypres; Fourteen Points; Lusitania; Paris Peace Conference; Treaties of Brest-Litovsk, Neuilly, Saint-Germain, Sèvres, Trianon, and Versailles; Edmund H.H. Allenby, Ferdinand Foch, John French, Douglas Haig, Paul von Hindenburg, Joseph-Jacques-Césaire Joffre, Erich Ludendorff, John Pershing.

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or Paraguayan War

(1864/65–70) Bloodiest conflict in Latin American history, fought between Paraguay and the allied countries of Argentina, Brazil, and Uruguay. The Paraguayan dictator Francisco Solano López (1827–70), objecting to Brazil's interference in the politics of neighbouring Uruguay, declared war on Brazil in 1864. The next year Argentina organized the Triple Alliance with Brazil and Uruguay. After three years of fighting, the allies annihilated the Paraguayan forces, but Solano López carried on a guerrilla war until he was killed. Paraguay was devastated by the war; its population was reduced by half, and territory covering some 55,000 sq mi (140,000 sq km) was annexed by Brazil and Argentina.

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(1701–14) Conflict arising from the disputed succession to the throne of Spain after the death of the childless Charles II. The Habsburg Charles had named the Bourbon Philip, duke d'Anjou, as his successor; when Philip took the Spanish throne as Philip V, his grandfather Louis XIV invaded the Spanish Netherlands. The former anti-French alliance from the War of the Grand Alliance was revived in 1701 by Britain, the Dutch Republic, and the Holy Roman emperor, who had been promised parts of the Spanish empire by earlier treaties of partition (1698, 1699). The English forces, led by the duke of Marlborough, won a series of victories over France (1704–09), including the Battle of Blenheim, which forced the French out of the Low Countries and Italy. The imperial general, Eugene of Savoy, also won notable victories. In 1711 conflicts within the alliance led to its collapse, and peace negotiations began in 1712. The war concluded with the Peace of Utrecht (1713), which marked the rise of the power of Britain at the expense of both France and Spain, and the Treaties of Rastatt and Baden (1714).

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(1733–38) European conflict waged ostensibly to determine the successor to Augustus II. Austria and Russia supported his son Augustus III, while most Poles, France, and Spain supported Stanisław I, a former Polish king (1704–09) and father-in-law of France's Louis XV. Stanisław was elected king in 1733, but a Russian threat forced him to flee, and Augustus was elected in his place. France, with Sardinia and Spain, declared war on Austria (1733), seeking to reclaim territory in Italy held by Austria. An inconclusive campaign ended in the preliminary Peace of Vienna (1735), which redistributed the disputed Italian territory and recognized Augustus as king. A final treaty was signed in 1738.

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(1879–83) Conflict involving Chile, Bolivia, and Peru over disputed territory on the mineral-rich Pacific coast. National boundaries in the region were not definitively established prior to the conflict, and in the 1870s Chile controlled nitrate fields claimed by Peru and Bolivia. When demand for nitrates rose, war broke out over the territory. Chile defeated both countries and took control of valuable mining areas in each; Bolivia lost its entire Pacific coast. A 1904 treaty gave Bolivian commerce freedom of transit through Chilean territory, but Bolivia continued to try to escape its landlocked status (see Chaco War). Peru foundered economically for decades after the war. A final accord between Peru and Chile was only reached in 1929 through U.S. mediation.

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(1689–97) Third major war of Louis XIV of France, in which his expansionist plans were blocked by an alliance led by Britain, the United Provinces of the Netherlands, and the Austrian Habsburgs. The deeper issue underlying the war was the rivalry between the Bourbon and Habsburg dynasties. Louis launched a campaign in the 1680s to position the Bourbons for future succession to the Spanish throne. To oppose him, the Habsburg emperor Leopold I joined other European nations in the League of Augsburg. The league proved ineffective, but in 1690 Britain, Brandenburg, Saxony, Bavaria, and Spain, alarmed at Louis's successes, joined with Leopold to form the Grand Alliance. As war broke out in Europe and in overseas colonies, including America (see King William's War), Louis found his military inadequately prepared, and France suffered heavy naval losses. In 1695 Louis started secret peace negotiations, which culminated in the Treaty of Rijswijk (1697). The underlying conflict between the Habsburg and Bourbon rulers and English-French conflicts remained unresolved and resurfaced four years later in the War of the Spanish Succession.

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(1778–79) Conflict in which Frederick II of Prussia prevented Joseph II of Austria from acquiring Bavaria. After the death of the Bavarian elector Maximilian Joseph (1727–77), his successor, Charles Theodore (1724–99), ceded Lower Bavaria to Austria. Frederick II responded by declaring war (1778). There was little fighting because each force was concerned with cutting its opponent's communications and denying it supplies. Short on supplies, soldiers foraged for potatoes; hence, the conflict was nicknamed the “potato war.” In 1779 Austria and Prussia signed a treaty giving Austria a fraction of the territory originally occupied.

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(1740–48) Group of related wars that took place after the death (1740) of Emperor Charles VI. At issue was the right of Charles's daughter Maria Theresa to inherit the Habsburg lands. The war began when Frederick II of Prussia invaded Silesia in 1740. His victory suggested that the Habsburg dominions were incapable of defending themselves, prompting other countries to enter the fray. The conflict was ended by the Treaty of Aix-la-Chapelle.

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(1667–68) Conflict between France and Spain over possession of the Spanish Netherlands. Louis XIV began the war on the pretext that the custom of devolution, whereby daughters of a first marriage were preferred to sons of subsequent marriages regarding property inheritance, should apply to sovereign territories also. That would mean that his wife, Marie-Thérèse (1638–1683), should succeed her father, Philip IV, in the Spanish Netherlands. The French army advanced into Flanders in May 1667 and easily secured its objectives. A peace was reached at Aix-la-Chapelle, whereby France gave up Franche-Comté but retained conquered towns in Flanders.

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U.S.-British conflict arising from U.S. grievances over oppressive British maritime practices in the Napoleonic Wars. To enforce its blockade of French ports, the British boarded U.S. and other neutral ships to check cargo they suspected was being sent to France and to impress seamen alleged to be British navy deserters. The U.S. reacted by passing legislation such as the Embargo Act (1807); Congress's War Hawks called for expulsion of the British from Canada to ensure frontier security. When the U.S. demanded an end to the interference, Britain refused, and the U.S. declared war on June 18, 1812. Despite early U.S. naval victories, notably the duel between the Constitution and the Guerrière, Britain maintained its blockade of eastern U.S. ports. A British force burned public buildings in Washington, D.C., including the White House, in retaliation for similar U.S. acts in York (Toronto), Can. The war became increasingly unpopular, especially in New England, where a separatist movement originated at the Hartford Convention. On Dec. 24, 1814, both sides signed the Treaty of Ghent, which essentially restored territories captured by each side. Before news of the treaty reached the U.S., its victory in the Battle of New Orleans led it to later proclaim the war a U.S. victory. Seealso Battle of Châteauguay; Chippewa; Thames; Isaac Hull; Francis Scott Key; Oliver Perry.

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(1955–75) Protracted effort by South Vietnam and the U.S. to prevent North and South Vietnam from being united under communist leadership. After the First Indochina War, Vietnam was partitioned to separate the warring parties until free elections could be held in 1956. Ho Chi Minh's popular Viet Minh party from the north was expected to win the elections, which the leader in the south, Ngo Dinh Diem, refused to hold. In the war that ensued, fighters trained in the north (the Viet Cong) fought a guerrilla war against U.S.-supported South Vietnamese forces; North Vietnamese forces later joined the fighting. At the height of U.S. involvement, there were more than half a million U.S. military personnel in Vietnam. The Tet Offensive of 1968, in which the Viet Cong and North Vietnamese attacked 36 major South Vietnamese cities and towns, marked a turning point in the war. Many in the U.S. had come to oppose the war on moral and practical grounds, and Pres. Lyndon B. Johnson decided to shift to a policy of “de-escalation.” Peace talks were begun in Paris. Between 1969 and 1973 U.S. troops were withdrawn from Vietnam, but the war was expanded to Cambodia and Laos in 1970. Peace talks, which had reached a stalemate in 1971, started again in 1973, producing a cease-fire agreement. Fighting continued, and there were numerous truce violations. In 1975 the North Vietnamese launched a full-scale invasion of the south. The south surrendered later that year, and in 1976 the country was reunited as the Socialist Republic of Vietnam. More than 2,000,000 people (including 58,000 Americans) died over the course of the war, about half of them civilians.

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Mostly legendary conflict between the Greeks and the people of Troy in western Asia Minor. It was dated by later Greeks to the 12th or 13th century BC. It is celebrated in Homer's Iliad and Odyssey, in Greek tragedy, and in Roman literature. In Homer's account the Trojan prince Paris ran off with the beautiful Helen, wife of Menelaus of Sparta, whose brother Agamemnon then led a Greek expedition to retrieve her. The war lasted 10 years; its participants included Hector, Achilles, Priam, Odysseus, and Ajax. Its end resulted from a ruse: The Greeks built a large wooden horse in which a raiding party hid. When the Greeks pretended to leave, the Trojans brought the horse into the walled city and the Greeks swarmed out, opening the gates to their comrades and sacking Troy, killing the men and enslaving the women. The extent of the legend's actual historical content is not known; excavations have revealed human habitation from 3000 BC to AD 1200, and there is evidence of violent destruction about 1250 BC.

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(1801–05) Conflict between the U.S. and Tripoli. The U.S. refused to continue paying tribute to the rulers of the North African Barbary Coast states, which had bought immunity from pirate attacks in the Mediterranean. The pasha of Tripoli demanded greater tribute and then declared war on the U.S. (1801). A U.S. naval squadron was sent to Tripolitan waters and fought several skirmishes, including a raid by Stephen Decatur. A U.S. naval blockade and an overland expedition from Egypt ended the war with a peace treaty favourable to the U.S.

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or Paraguayan War

(1864/65–70) Bloodiest conflict in Latin American history, fought between Paraguay and the allied countries of Argentina, Brazil, and Uruguay. The Paraguayan dictator Francisco Solano López (1827–70), objecting to Brazil's interference in the politics of neighbouring Uruguay, declared war on Brazil in 1864. The next year Argentina organized the Triple Alliance with Brazil and Uruguay. After three years of fighting, the allies annihilated the Paraguayan forces, but Solano López carried on a guerrilla war until he was killed. Paraguay was devastated by the war; its population was reduced by half, and territory covering some 55,000 sq mi (140,000 sq km) was annexed by Brazil and Argentina.

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(1898) Conflict between the U.S. and Spain that ended Spanish colonial rule in the New World. The war originated in Cuba's struggle for independence. The newspapers of William Randolph Hearst fanned U.S. sympathy for the rebels, which increased after the unexplained destruction of the U.S. warship Maine on Feb. 15, 1898. Congress passed resolutions declaring Cuba's right to independence and demanding that Spain withdraw its armed forces. Spain declared war on the U.S. on April 24. Commo. George Dewey led the naval squadron that defeated the Spanish fleet in the Philippines (see Battle of Manila Bay) on May 1, and Gen.William Shafter led regular troops and volunteers (including future U.S. president Theodore Roosevelt and his Rough Riders) in the destruction of Spain's Caribbean Sea fleet near Santiago, Cuba (July 17). In the Treaty of Paris (December 10), Spain renounced all claim to Cuba and ceded Guam, Puerto Rico, and the Philippines to the U.S., marking the U.S.'s emergence as a world power.

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(1701–14) Conflict arising from the disputed succession to the throne of Spain after the death of the childless Charles II. The Habsburg Charles had named the Bourbon Philip, duke d'Anjou, as his successor; when Philip took the Spanish throne as Philip V, his grandfather Louis XIV invaded the Spanish Netherlands. The former anti-French alliance from the War of the Grand Alliance was revived in 1701 by Britain, the Dutch Republic, and the Holy Roman emperor, who had been promised parts of the Spanish empire by earlier treaties of partition (1698, 1699). The English forces, led by the duke of Marlborough, won a series of victories over France (1704–09), including the Battle of Blenheim, which forced the French out of the Low Countries and Italy. The imperial general, Eugene of Savoy, also won notable victories. In 1711 conflicts within the alliance led to its collapse, and peace negotiations began in 1712. The war concluded with the Peace of Utrecht (1713), which marked the rise of the power of Britain at the expense of both France and Spain, and the Treaties of Rastatt and Baden (1714).

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or Boer War

War fought between Great Britain and the two Boer (see Afrikaner) republics—the South African Republic (Transvaal) and the Orange Free State—from 1899 to 1902. It was precipitated by the refusal of the Boer leader Paul Kruger to grant political rights to Uitlanders (“foreigners,” mostly English) in the interior mining districts and by the aggressiveness of the British high commissioner, Alfred Milner. Initially the Boers defeated the British in major engagements and besieged the key towns of Ladysmith, Mafikeng, and Kimberley; but British reinforcements under H.H. Kitchener and F.S. Roberts relieved the besieged towns, dispersed the Boer armies, and occupied Bloemfontein, Johannesburg, and Pretoria (1900). When Boer commando attacks continued, Kitchener implemented a scorched-earth policy: Boer farms were destroyed and Boer civilians were herded into concentration camps. More than 20,000 men, women, and children (including black Africans) died as a result, causing international outrage. The Boers finally accepted defeat at the Peace of Vereeniging.

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or Italic War or Marsic War

(90–89 BC) Rebellion waged by ancient Rome's Italian allies (Latin, socii). The allies in central and southern Italy had aided Rome in its wars, but they were denied the privileges of Roman citizenship. The people of central Italy's hills—the Marsi in the north and the Samnites in the south—organized a confederacy and began an uprising for independence, winning victories over Roman armies in the north and south. After Rome granted citizenship to those who had not revolted and those who would immediately lay down their arms, Italian interest in the struggle declined. Sulla defeated the weakened rebels in the south, and legislation was passed to unify Italy south of the Po River.

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(1756–63) Major European conflict between Austria and its allies France, Saxony, Sweden, and Russia on one side against Prussia and its allies Hanover and Britain on the other. The war arose out of Austria's attempt to win back the rich province of Silesia, taken by Prussia in the War of the Austrian Succession. Early victories by Frederick II the Great in Saxony and Bohemia (1756–58) were offset by a decisive Prussian defeat by Austria and Russia near Frankfurt (1759). After inconclusive fighting in 1760–61, Frederick concluded a peace with Russia (1762) and drove the Austrians from Silesia. The war also involved the overseas colonial struggles between Britain and France in North America (see French and Indian War) and in India. The European conflict was settled with the Treaty of Hubertusburg, by which Frederick confirmed Prussia's stature as a major European power.

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(1904–05) Conflict between Russia and Japan over territorial expansion in East Asia. After Russia leased the strategically important Port Arthur (now Lüshun, China) and expanded into Manchuria (northeastern China), it faced the increasing power of Japan. When Russia reneged on its agreement with Japan to withdraw troops from Manchuria, the Japanese fleet attacked the Russia naval squadron at Port Arthur and began a siege of the city in February 1904. Japanese land forces cut the Russian army off from coming to aid Port Arthur and pushed it back to Mukden (now Shenyang). The reinforced Russian army took the offensive in October, but poor military leadership blunted its effectiveness. After the long Japanese siege of Port Arthur, in January 1905 the corrupt Russian commander surrendered the garrison without consulting his officers, despite adequate stores and ammunition for its continued defense. Heavy fighting around Mukden ended in March 1905 with the withdrawal of Russian troops under Aleksey Kuropatkin. The decisive naval Battle of Tsushima gave the Japanese the upper hand and brought Russia to the peace table. With the signing of the Treaty of Portsmouth, Russia abandoned its expansionist policy in eastern Asia and Japan gained effective control of Korea and much of Manchuria.

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or Winter War

(1939–40) War waged by the Soviet Union against Finland at the start of World War II, following the signing of the German-Soviet Nonaggression Pact. When Finland refused to grant the Soviets a naval base and other concessions, Soviet troops attacked on several fronts in November 1939. The heavily outnumbered Finns under Carl Gustav Emil Mannerheim put up a skillful defense until February 1940, when heavy Russian bombardments breached the Finns' southern defenses. A peace treaty in March 1940 ceded western Karelia to Russia and allowed construction of a Soviet naval base on the Hanko peninsula.

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(1702–13) Second in a series of wars between Britain and France for control of North America. It was the American phase of the War of the Spanish Succession. American colonial settlements along the New York and New England borders with Canada were raided by French forces and their Indian allies. The British capture of Port Royal (1710) resulted in French-held Acadia's becoming the British province of Nova Scotia. Under the Treaty of Utrecht (1713), Britain also acquired Newfoundland and the Hudson Bay region from France.

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Any of various floating, warm-water marine cnidarians (genus Physalia, class Hydrozoa) found worldwide but mostly in the Gulf Stream and the Indian and Pacific oceans. The medusa-form body consists of a translucent, jellylike, gas-filled float, which may be 3–12 in. (9–30 cm) long. Polyps beneath the float bear hanging tentacles up to 165 ft (50 m) long. Nematocysts on some polyps paralyze fish and other prey. Other polyps then attach to, spread over, and digest the victim. A third type of polyp is involved in reproduction. The painful sting of Physalia can cause fever, shock, or disruption of heart and lung function.

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(1733–38) European conflict waged ostensibly to determine the successor to Augustus II. Austria and Russia supported his son Augustus III, while most Poles, France, and Spain supported Stanisław I, a former Polish king (1704–09) and father-in-law of France's Louis XV. Stanisław was elected king in 1733, but a Russian threat forced him to flee, and Augustus was elected in his place. France, with Sardinia and Spain, declared war on Austria (1733), seeking to reclaim territory in Italy held by Austria. An inconclusive campaign ended in the preliminary Peace of Vienna (1735), which redistributed the disputed Italian territory and recognized Augustus as king. A final treaty was signed in 1738.

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or Gulf War

(1990–91) International conflict triggered by Iraq's invasion of Kuwait in August 1990. Though justified by Iraqi leader Ssubdotaddām Hsubdotussein on grounds that Kuwait was historically part of Iraq, the invasion was presumed to be motivated by Iraq's desire to acquire Kuwait's rich oil fields and expand its power in the region. The United States, fearing Iraq's broader strategic intentions and acting under UN auspices, eventually formed a broad coalition, which included a number of Arab countries, and began massing troops in northern Saudi Arabia. When Iraq ignored a UN Security Council deadline for it to withdraw from Kuwait, the coalition began a large-scale air offensive (Jan. 16–17, 1991). Ssubdotaddām responded by launching ballistic missiles against neighbouring coalition states as well as Israel. A ground offensive by the coalition (February 24–28) quickly achieved victory. Estimates of Iraqi military deaths range up to 100,000; coalition forces lost about 300 troops. The war also caused extensive damage to the region's environment. The Iraqi regime subsequently faced widespread popular uprisings, which it brutally suppressed. A UN trade embargo remained in effect after the end of the conflict, pending Iraq's compliance with the terms of the armistice. The foremost term was that Iraq destroy its nuclear, biological, and chemical weapons programs. The embargo continued into the 21st century and ceased only after the Iraq War started in 2003.

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(1808–14) Part of the Napoleonic Wars, fought on the Iberian Peninsula. After French forces occupied Portugal (1807) and Napoleon installed his brother Joseph Bonaparte as king of Spain (1808), a rebellion in Madrid began what was called in Spain “the War of Independence,” and insurrections soon erupted in other cities. By 1810 the French overcame the Spanish rebels in Madrid and elsewhere in Spain. Meanwhile, the British under the future duke of Wellington landed in Portugal (1808), where they fought the French in inconclusive campaigns until 1812. After Napoleon withdrew French forces to bolster his invasion of Russia, Wellington began his gradual advance into Spain. The British victory at the Battle of Vitoria (1813) and their march into southwestern France forced the French to withdraw from Spain and to reinstall Ferdinand VII as king (1814).

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(431–404 BC) War fought between Athens and Sparta, the leading city-states of ancient Greece, along with their allies, which included nearly every other Greek city-state. Its principal cause was a fear of Athenian imperialism. The Athenian alliance relied on its strong navy, the Spartan alliance on its strong army. The war fell into two periods, separated by a six-year truce. Fighting broke out in 431, with Pericles commanding the Athenians. In the first 10 years, Archidamus led the Spartans to defeats. Plague struck Athens in 429, killing Pericles and much of the army. In 428 Cleon almost convinced Athens to massacre the rebellious citizens of Mytilene on Lesbos, but Athens rescinded the order. In 421 both states agreed to accept the Peace of Nicias. This lasted six years, until Athens launched its disastrous Sicilian expedition. By 413 Athens's forces were demolished. In 411 an oligarchy briefly took power. When democratic leaders were restored by the navy later that year, they refused Spartan peace offers, and the war continued until 405, when the Athenian navy was destroyed at the Battle of Aegospotami with Persian help. Under blockade, Athens surrendered in 404. Its empire was dismantled, and the Spartans installed the Thirty Tyrants.

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(1879–83) Conflict involving Chile, Bolivia, and Peru over disputed territory on the mineral-rich Pacific coast. National boundaries in the region were not definitively established prior to the conflict, and in the 1870s Chile controlled nitrate fields claimed by Peru and Bolivia. When demand for nitrates rose, war broke out over the territory. Chile defeated both countries and took control of valuable mining areas in each; Bolivia lost its entire Pacific coast. A 1904 treaty gave Bolivian commerce freedom of transit through Chilean territory, but Bolivia continued to try to escape its landlocked status (see Chaco War). Peru foundered economically for decades after the war. A final accord between Peru and Chile was only reached in 1929 through U.S. mediation.

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or Mexican-American War

(1846–48) War between the U.S. and Mexico. It grew from a border dispute after the U.S. annexed Texas in 1845; Mexico claimed that the southern border of Texas was the Nueces River, while the U.S. claimed it was the Rio Grande. A secret mission by John Slidell to negotiate the dispute and purchase New Mexico and California for up to $30 million was aborted when Mexico refused to receive him. In response to the snub, Pres. James Polk sent troops under Zachary Taylor to occupy the disputed land between the two rivers. In April 1846 Mexican troops crossed the Rio Grande and attacked Taylor's troops; Congress approved a declaration of war in May. Ordered to invade Mexico, Taylor captured Monterrey and defeated a large Mexican force under Antonio Santa Anna at the Battle of Buena Vista in February 1847. Polk then ordered Gen. Winfield Scott to move his army by sea to Veracruz, capture the city, and march inland to Mexico City. Scott followed the plan, meeting resistance at Cerro Gordo and Contreras, and entered Mexico City in September. Under the Treaty of Guadalupe Hidalgo, Mexico ceded to the U.S. nearly all of present New Mexico, Utah, Nevada, Arizona, California, Texas, and Colorado for $15,000,000 and U.S. assumption of its citizens' claims against Mexico. Casualties included about 13,000 American deaths, all but 1,700 of which were caused by disease. The war, which made a national hero of Taylor, reopened the slavery-extension issue supposedly settled by the Missouri Compromise.

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(1950–53) Conflict arising after the post-World War II division of Korea, at latitude 38° N, into North Korea and South Korea. At the end of World War II, Soviet forces accepted the surrender of Japanese forces north of that line, as U.S. forces accepted Japanese surrender south of it. Negotiations failed to reunify the two halves, the northern half being a Soviet client state and the southern half being backed by the U.S. In 1950 North Korea invaded South Korea, and U.S. Pres. Harry Truman ordered troops to assist South Korea. The UN Security Council, minus the absent Soviet delegate, passed a resolution calling for the assistance of all UN members in halting the North Koreans. At first North Korean troops drove the South Korean and U.S. forces down to the southern tip of the Korean peninsula, but a brilliant amphibious landing at Inch'ŏn, conceived by Gen. Douglas MacArthur, turned the tide in favour of the UN troops, who advanced near the border of North Korea and China. The Chinese then entered the war and drove the UN forces back south; the front line stabilized at the 38th parallel. MacArthur insisted on voicing his objections to U.S. war aims in a public manner and was relieved of his command by Truman. U.S. Pres. Dwight D. Eisenhower participated in the conclusion of an armistice that accepted the front line as the de facto boundary between the two Koreas. The war resulted in the deaths of approximately 2,000,000 Koreans, 600,000 Chinese, 37,000 Americans, and 3,000 Turks, Britons, and other nationals in the UN forces.

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(1689–97) Battle for North American territory between Britain, under King William III, and France. The war, which was the North American extension of the War of the Grand Alliance, involved French Canadians and New England colonists and their Indian allies. The British captured Port Royal, Acadia (later Nova Scotia), but failed to take Quebec. The French, under the count de Frontenac, won skirmishes at Schenectady, N.Y., and in New England but failed to take Boston. The war ended with the Treaty of Rijswijk (1697). Seealso French and Indian War.

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(1675–76) Bloodiest conflict between American colonists and Indians in 17th-century New England. By 1660 colonial settlers, no longer dependent on Indians for survival, had pushed into Indian territory in Massachusetts, Connecticut, and Rhode Island. To protect their lands, the Wampanoag chief King Philip (Metacom) organized a federation of tribes, which in 1675 destroyed several frontier settlements. In retaliation the colonial militia burned Indian villages and crops. After Philip's death in 1676, Indian resistance collapsed. An estimated 600 settlers and 3,000 Indians were killed in the conflict.

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(1744–48) Inconclusive struggle between France and Britain for mastery of North America. Also called the American phase of the War of the Austrian Succession, the war involved disputes over boundaries of Nova Scotia and northern New England and control of the Ohio Valley. After bloody border raids by both sides, aided by their Indian allies, they signed the Treaty of Aix-la-Chapelle (1748), which restored conquered territory but failed to resolve colonial issues. Seealso French and Indian War.

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or Second Persian Gulf War

Brief conflict in 2003 between Iraq and a combined force of troops largely from the U.S. and Great Britain; and a subsequent U.S.-led occupation of Iraq and protracted Iraqi armed insurgency against it. The trade embargo and weapons-inspection process that the UN imposed on Iraq following the Persian Gulf War (1990–91) had partly fallen into abeyance by 2001. U.S. Pres. George W. Bush argued that the September 11 attacks on the U.S. in that same year highlighted the threat to U.S. security posed by hostile countries such as Iraq. In November 2002 the UN issued Security Council Resolution 1441 demanding that Iraq readmit weapons inspectors and comply with all previous resolutions. Although inspectors did return to Iraq, Bush and Blair declared in early 2003 (despite objections by many world leaders) that Iraq was continuing to hinder UN inspections and that it still retained proscribed weapons. On March 20 the U.S. and Britain (with smaller troop contingents from other countries) launched a series of air attacks on Iraq, and a ground invasion followed. Iraqi forces were rapidly defeated, and on April 9 U.S. forces took control of the capital, Baghdad. British forces completed their occupation of the southern city of Al-Bassubdotrah the same day, and by May 1 the major combat operations of the invasion had been completed. However, the U.S. and other occupying forces were soon embroiled in escalating guerrilla warfare in Iraq that hindered Iraq's recovery and killed thousands of soldiers and tens of thousands of civilians. The war, long opposed by many throughout the world, also became increasingly unpopular in the U.S.

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(1980–90) Protracted and indecisive conflict prompted by Iraq's invasion of its eastern neighbour. Following the 1979 Iranian revolution, the Iraqi leadership sought to exploit Iran's military and political chaos in order to resolve border disputes, gain control of Iran's oil-rich western (largely Arab) province, and achieve hegemony in the Persian Gulf. Iraq was successful early (1980–82) but began to lose ground and sought to negotiate peace. Iran refused, and the war turned into a bloody stalemate that included the first use of chemical warfare since World War I (1914–18). After additional Iraqi advances, Iran agreed to a cease-fire in 1988. Peace was concluded only when Iraq invaded another neighbour, Kuwait, in 1990. Seealso Ssubdotaddām Hsubdotussein; Ruhollah Khomeini.

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Cluster of illnesses in veterans of the Persian Gulf War (1990–91). These illnesses are characterized by variable and nonspecific symptoms such as fatigue, muscle and joint pains, headaches, memory loss, and posttraumatic stress reactions. It is believed to be caused by exposure to chemicals called anticholinesterases, which are found in nerve toxins, insecticides, and prophylactic anti-nerve toxin drugs. The disorder does not appear to be fatal but can be associated with considerable distress and disability.

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(1689–97) Third major war of Louis XIV of France, in which his expansionist plans were blocked by an alliance led by Britain, the United Provinces of the Netherlands, and the Austrian Habsburgs. The deeper issue underlying the war was the rivalry between the Bourbon and Habsburg dynasties. Louis launched a campaign in the 1680s to position the Bourbons for future succession to the Spanish throne. To oppose him, the Habsburg emperor Leopold I joined other European nations in the League of Augsburg. The league proved ineffective, but in 1690 Britain, Brandenburg, Saxony, Bavaria, and Spain, alarmed at Louis's successes, joined with Leopold to form the Grand Alliance. As war broke out in Europe and in overseas colonies, including America (see King William's War), Louis found his military inadequately prepared, and France suffered heavy naval losses. In 1695 Louis started secret peace negotiations, which culminated in the Treaty of Rijswijk (1697). The underlying conflict between the Habsburg and Bourbon rulers and English-French conflicts remained unresolved and resurfaced four years later in the War of the Spanish Succession.

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or Franco-German War

(1870–71) War in which a coalition of German states led by Prussia defeated France, ending French hegemony in continental Europe and creating a unified Germany. The immediate cause was the candidacy of Prince Leopold of Hohenzollern-Sigmaringen for the Spanish throne, which raised the possibility of a combination of Prussia and Spain against France. Following diplomatic maneuvers to block Leopold's candidacy, the Prussian chancellor Otto von Bismarck published the Ems Telegram to provoke the French government into declaring war, which it did. The other German states sided with Prussia, and German troops under Gen. Helmuth von Moltke, superior in numbers and organization, scored repeated victories. After Napoleon III surrendered at the Battle of Sedan, French resistance was carried on by a new government, which deposed the emperor and established the Third Republic. Paris surrendered, but while treaty negotiations were going on, an insurrection by radicals in Paris created a short-lived government, the Paris Commune. After its suppression, a harsh peace treaty was implemented: Germany annexed Alsace and half of Lorraine, and France was occupied until a large indemnity was paid. The German empire was established when William I of Prussia was proclaimed German emperor in 1871. The peace was an unstable one, marked by France's determination to recover Alsace-Lorraine and Germany's mounting imperialism, led by Prussian militarism. Their mutual animosity was a driving force that led to World War I.

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(1667–68) Conflict between France and Spain over possession of the Spanish Netherlands. Louis XIV began the war on the pretext that the custom of devolution, whereby daughters of a first marriage were preferred to sons of subsequent marriages regarding property inheritance, should apply to sovereign territories also. That would mean that his wife, Marie-Thérèse (1638–1683), should succeed her father, Philip IV, in the Spanish Netherlands. The French army advanced into Flanders in May 1667 and easily secured its objectives. A peace was reached at Aix-la-Chapelle, whereby France gave up Franche-Comté but retained conquered towns in Flanders.

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(October 1853–February 1856) War fought mainly in the Crimea between the Russians and an alliance consisting of the Ottoman empire, Britain, France, and Sardinia-Piedmont. It arose from the conflict of great powers in the Middle East and was more directly caused by Russian demands to exercise protection over the Orthodox subjects of the Ottoman sultan. The war was managed and commanded poorly by both sides. Battles were fought at the Alma River, Balaklava, and Inkerman, before the besieged Sevastopol was taken by the allies. Disease accounted for many of the approximately 250,000 men lost by each side. After Austria threatened to join the allies, Russia accepted preliminary peace terms, which were formalized at the Congress of Paris. The war did not settle the relations of the powers in Eastern Europe, but it did alert Alexander II to the need to modernize Russia.

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(1778–79) Conflict in which Frederick II of Prussia prevented Joseph II of Austria from acquiring Bavaria. After the death of the Bavarian elector Maximilian Joseph (1727–77), his successor, Charles Theodore (1724–99), ceded Lower Bavaria to Austria. Frederick II responded by declaring war (1778). There was little fighting because each force was concerned with cutting its opponent's communications and denying it supplies. Short on supplies, soldiers foraged for potatoes; hence, the conflict was nicknamed the “potato war.” In 1779 Austria and Prussia signed a treaty giving Austria a fraction of the territory originally occupied.

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(1740–48) Group of related wars that took place after the death (1740) of Emperor Charles VI. At issue was the right of Charles's daughter Maria Theresa to inherit the Habsburg lands. The war began when Frederick II of Prussia invaded Silesia in 1740. His victory suggested that the Habsburg dominions were incapable of defending themselves, prompting other countries to enter the fray. The conflict was ended by the Treaty of Aix-la-Chapelle.

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(1838–39) Bloodless conflict over the disputed boundary between the U.S. state of Maine and the British Canadian province of New Brunswick. As settlers from both countries moved into the disputed Aroostook area, officials and bands of men from both sides made arrests and took prisoners of “trespassers.” In 1839 U.S. and Canadian troops were ordered to the area. A truce allowed joint occupancy of the territory until 1842, when a satisfactory settlement was reached.

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(1839–46) Civil protest by leaseholding farmers in upper New York state. Protesting outdated laws based on semifeudal leaseholding practices of the early Dutch estate owners, the leaseholders of Albany county in 1839 refused to pay back rent. The governor called out the militia to quell the violence. Sporadic acts of resistance against rent and tax collection spread across the state, and in 1845 the governor declared martial law. In 1846 a new state constitution abolished the leasehold system.

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Warfare in which the opposing sides attack, counterattack, and defend from sets of trenches dug into the ground. It was developed by Sébastien Le Prestre de Vauban in the 17th century for laying siege to fortresses. Its defensive use was first institutionalized as a tactic during the American Civil War. It reached its highest development in World War I. Little used in World War II, it reappeared in the Iran-Iraq War in the 1980s. A typical construction consisted of two to four parallel trenches, each dug in a zigzag, protected by sandbags, and floored with wooden planks. The parallel trenches were connected by a series of communication trenches dug roughly perpendicular to them. The first row was fronted by barbed wire and contained machine-gun emplacements; the rear trenches housed most of the troops. Increased use of tanks marked the end of trench warfare, since tanks were invulnerable to the machine-gun and rifle fire used by entrenched soldiers.

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Use of propaganda against an enemy, supported by whatever military, economic, or political measures are required, and usually intended to demoralize an enemy or to win it over to a different point of view. It has been carried on since ancient times. The conquests of Genghis Khan were aided by expertly planted rumours about large numbers of ferocious Mongol horsemen in his army. Specialized units were a major part of the German and Allied forces in World War II and the U.S. armed forces in the Korean and Vietnam wars. Strategic psychological warfare is mass communications directed to a very large audience or over a considerable expanse of territory; tactical psychological warfare implies a direct connection with combat operations (e.g., the surrender demand). Consolidation psychological warfare consists of messages distributed to the rear of one's own advancing forces for the sake of protecting the line of communications, establishing military government, and carrying out administrative tasks within such a government.

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Military operations conducted on, under, or over the sea and waged against other seagoing vessels or targets on land or in the air. The earliest naval attacks were raids by the armed men of a tribe or town using fishing boats or merchant ships. The first warships were galleys, replaced in the 16th and 17th centuries by sail-driven warships equipped with cannons. The British victory over the Spanish Armada (1588) marked a major development: British galleons refused to allow the Spanish ships to get close enough for boarding and hand-to-hand combat and instead pounded them with guns of superior firing capability. Ships of the line and cruisers emerged in the 17th and 18th centuries. In the later 19th century, steam replaced sail propulsion, and ironclads offered greater protection against the increasing power of guns. The battleship, developed in these years, reigned until World War II, when the Pearl Harbor attack proved that bombers launched from aircraft carriers could sink any and all surface ships. Since then, naval air power—missiles as well as carrier-based planes—has been the primary weapon of the world's fleets. Submarines also play a major role in naval warfare.

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Use of economic measures by governments engaged in international conflict. These may include export and import controls, shipping controls, trade agreements with neutral nations, and so on. Economic warfare among belligerents began with the blockade and interception of contraband. In World War II it was broadened to include economic pressure applied to neutral countries from which the enemy obtained its supplies. In the Cold War it often involved using measures such as an embargo to deny potential enemies goods that might contribute to their war-making ability.

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Use of lethal or incapacitating chemical weapons in war, and the methods of combating such agents. Chemical weapons include choking agents such as the chlorine and phosgene gas employed first by the Germans and later by the Allies in World War I; blood agents such as hydrogen cyanide or cyanogen gas, which block red blood cells from taking up oxygen; blister agents such as sulfur gas and Lewisite, also dispensed as a gas, which burn and blister the skin; and nerve agents such as Tabun, Sarin, Soman, and VX, which block the transmission of nerve impulses to the muscles, heart, and diaphragm. The horrific casualties suffered in World War I led to the 1925 Geneva Protocol, which made it illegal to employ chemical weapons but did not ban their production. Chemical weapons were used a number of times afterward, most notably by Italy in Ethiopia (1935–36), by Japan in China (1938–42), by Egypt in Yemen (1966–67), and by Iran and Iraq against each other (1984–88). During the Cold War the Soviet Union and U.S. built up enormous chemical arsenals; these were dismantled under the terms of the 1993 Chemical Weapons Convention, which prohibits all development, production, acquisition, stockpiling, or transfer of such weapons. Not all countries have signed the convention, and many are suspected of pursuing clandestine chemical programs. Many military forces have adopted various defensive measures, including chemical sensors, protective garments and gas masks, decontaminants, and injectable antidotes, and some have reserved the option of retaliating in kind to any chemical attack. In 1995 a religious cult killed 12 civilians and injured thousands more with Sarin gas in Tokyo; this pointed out the power of chemical agents as weapons of terror as well as the difficulty of protecting civilian populations. Seealso biological warfare.

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or germ warfare

Military use of disease-producing or poisonous agents, and the means for defending against such agents. Biological warfare agents include many bacteria, such as those which cause anthrax, brucellosis, and typhus; viruses that cause diseases such as equine encephalitis; fungi such as rice blast, cereal rust, wheat smut, and potato blight; and toxins such as botulinum and ricin that are extracted from living organisms. Biological warfare dates from ancient times when warring groups would try to poison enemy soldiers with rotting or diseased corpses, infect cattle and horses, or spread contagion through civilian populations. Following the horrors of World War I, a 1925 Geneva Protocol prohibited the use of biological agents in warfare; however, this did not prevent Japan from using them in China during World War II. During the Cold War the Soviet Union as well as the U.S. and its allies built huge stockpiles of biological agents. Both sides signed the 1972 Biological Weapons Convention, which prohibits the production, stockpiling, or development of biological weapons and requires the destruction of existing stockpiles, but the Soviets conducted a clandestine program until the 1990s. Biological weapons programs can be concealed easily, and the 1972 convention contains no provisions for inspection and reporting. As a result, many states have been suspected of developing biological warfare agents, and some modern armed forces have prepared defensive measures. These include battlefield sensors, protective garments and masks, sterilizing agents, and vaccines.

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Military operations directed against hostile shores and characterized by attacks launched from the sea by naval and landing forces. It has been conducted since ancient times. The Greeks attacking Troy (1200 BC) had to make a shore landing, as did the Persian invaders of Greece prior to the Battle of Marathon (490 BC). The British-led landings at Gallipoli (1915) were the main amphibious assault in World War I. The Allies of World War II found amphibious tactics essential in the island-hopping Pacific campaign and in the famous D-Day of the Normandy campaign, which still ranks as the greatest amphibious assault in history. Amphibious warfare's greatest advantage is its mobility and flexibility; its greatest limitation is that the attacker must start from nothing to build up strength ashore. Modern amphibious forces attempt to overcome this by fielding larger and more efficient landing vessels and also by using helicopters and short-takeoff and -landing airplanes to deploy troops beyond the hostile shore.

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Military operations conducted by airplanes, helicopters, or other aircraft against aircraft or targets on the ground and in the water. Air warfare did not become important until World War I (1914–18). The British, French, German, Russian, and Italian armed forces had flying units, including biplanes armed with machine guns for “dogfights” with enemy fighter aircraft. Zeppelins and larger airplanes carried out bombing raids. The 1920s and '30s saw the development of the monoplane, the all-metal fuselage, and the aircraft carrier. During World War II (1939–45), the Battle of Britain was the first fought exclusively in the air, the Battle of the Coral Sea was the first between carrier-based aircraft, and the atomic bombings of Hiroshima and Nagasaki were the first use of nuclear-armed bombers. In the jet age, air power has continued to be used in strategic bombing of an enemy's home territory (as in the Vietnam War, 1965–74), destroying enemy air forces (as in the Arab-Israeli wars), attacking and defending carrier-based naval fleets (as in the Falkland Islands War, 1982), and supporting ground forces (as in the Persian Gulf War, 1990–91).

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