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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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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Warfare refers to the conduct of conflict between opponents, and usually involves escalation of aggression from the proverbial "war of words" between politicians and diplomats to full-scale armed conflicts, waged until one side accepts defeat or peace terms are agreed on. Warfare between groups, and even more so between military organisations, require a degree of planning and application of military strategy to be conducted effectively in reaching their stated or assumed objectives and goals.
All of these categories usually fall into one of two broader categories: High intensity and low intensity warfare. High intensity warfare is between two superpowers or large countries fighting for political reasons. Low intensity warfare involves counterinsurgency, guerilla warfare and specialized types of troops fighting revolutionaries.