A blockade is any effort to prevent supplies, troops, information or aid from reaching an opposing force. Blockades are the cornerstone to nearly all military campaigns and the tool of choice for economic warfare on an opposing nation. The International Criminal Court plans to include blockades against coasts and ports in its list of acts of war in 2009.
Blockades can take any number of forms from a simple garrison of troops along a main roadway to utilizing dozens or hundreds of surface combatant ships in securing a harbor, denying its use to the enemy, and even in cutting off or jamming broadcast signals from radio or television. As a military operation, blockades have been known to be the deciding factor in winning or losing a war.
Blockades have been a part of war even in the classical antiquity
, both as part of a land siege
and as naval blockades. The Spartan
blockade after the battle of Aegospotami
for instance, eventually forced Athens
to surrender in the Peloponnesian War
Besides depriving the enemy of resources and trade, blockades were also used to force the enemy fleet to attack. The British admiral Horatio Nelson
for instance, applied a so called loose blockade at Cádiz
in 1805. In a loose blockade the blockading fleet is located behind the horizon in order to lure the enemy fleet out of the safety of the harbor. This is exactly what Villeneuve
's fleet did, resulting in the battle of Trafalgar
Until the 19th century blockades were always a part of a war. This changed in 1827 when France, Russia and the United Kingdom came to aid the First Hellenic Republic
by blockading the Ottoman occupied coast. Although it led to the battle of Navarino
, no war was declared and as such it is considered the first pacific blockade. The first truly pacific blockade was the British Blockade of the Republic of New Granada
in 1837, put in place to persuade New Granada to release an imprisoned British consul.
Act of War
A blockade is defined by Encyclopedia Britannica as an "an act of war by which a belligerent prevents access to or departure from a defined part of the enemy’s coasts.
Whether or not a blockade was seen as lawful depended on the national laws of the nations whose trade was influenced by the blockade. The Brasilian
blockade of Río de la Plata
in 1826, for instance, was considered lawful according to British law, but unlawful according to French and American law. The latter two countries announced they would actively defend their trade fleets, while Britain was forced to steer for a peaceful solution between Brasil and Argentina
In international law blockades were first defined at the Congress of Paris in 1856. One of the decisions stated that blockades had to be effective to be lawful. This banned so called paper blockades, blockades that were declared to the blockaded nation, but were not actively enforced. Such a blockade did however allow the blockading party to seize the cargo of neutral states trading with blockaded harbors. At the Declaration of London in 1909 another attempt was made to further protect the rights of neutral traders. The treaty was only ratified by a few nations, preventing any application of the agreements. Parts of it were however applied during blockades in the First World War.
Since 1945 the UN Security Council determines the legal status of blockades and by article 42 of the UN Charter the Council can also apply blockades.
Blockades are planned around four general rules:
- Value of thing to become blockaded
- Blockading strength is equal to or greater than the opposing force
- Suitability of terrain to aid in the blockade
- Willpower to maintain the blockade
First, the value of the item being blockaded must warrant the need to blockade. For example, during the 1962 Cuban Missile Crisis, the items to be blockaded (or "quarantined", the more legally- and politically-neutral term selected by President John F. Kennedy) were medium-range missiles, capable of delivering nuclear weaponry, bound for Cuba. The need for the blockade was high because of the value of the missiles as a military threat against the United States.
Second, the strength of the blockading force must be equal to or greater in strength than the opposition. The blockade is only successful if the 'thing' is prevented from reaching its receiver. Again the Cuban blockade illustration shows that the United States put to sea a number of warships to inspect and blockade the waters around Cuba. This show of strength showed the U.S. Navy forces were much larger and stronger in the area compared to their Soviet Navy counterparts.
Third, in the case of land blockades, choosing suitable terrain. Knowing where the force will be travelling through will help the blockader in choosing territory to aid them: for example, forcing a garrison between a high mountain pass in order to bottleneck the opposing force.
Fourth, willpower to maintain a blockade. The success of a blockade is based almost entirely on the will of the people to maintain it. The Cuban blockade is an example of maintaining willpower to block the missiles from reaching Cuba despite the risk of starting a world wide nuclear war.
Historical blockades include:
- The Spartan blockade of Athens following the Battle of Aegospotami, depriving Athens of the ability to import grain or communicate with its empire.
- The Dutch Republic's blockade of the Scheldt between 1585 and 1792, denying Spanish-ruled Antwerp's access to international trade and shifting much of its trade to Amsterdam.
- British blockade of France and its allies during the French Revolutionary War and Napoleonic War
- British blockade of the United States east coast during the War of 1812
- Danish blockade of Germany during the First Schleswig War, starting in 1848
- Union Blockade - the Union blockading the coasts of the Confederacy during the American Civil War
- Battle of Iquique during the War of the Pacific
- British naval blockade of Germany during World War I as a part of the First Battle of the Atlantic resulted in the death of about 750,000 civilians during the War. As the blockade was continued after the Armistice of November 1918 in the Aftermath of World War I in order to force Germany to sign the Treaty of Versailles in June 1919, many more had to die from starvation.
- The Second Battle of the Atlantic during World War II
- United States blockade of Japan during World War II
- The German blockade of the Scheldt between September 1944 and November 1944, denying to allied shipping use of the port of Antwerp. (See Battle of the Scheldt)
- Soviet land blockade of West Berlin, 1948–1949, known as the Berlin Blockade.
- Egyptian blockades of the Straits of Tiran prior to the 1956 Suez War and the 1967 Arab-Israeli War.
- United States blockade of Cuba during the Cuban missile crisis in 1962
- India blockade of East Pakistan during the 1971 Bangladesh War
- NATO blockade of the Federal Republic of Yugoslavia 1993–1996 during Operation Sharp Guard
- Israeli sea and land blockade of the Gaza Strip since the outbreak of the Second Intifada (2000) and up to the present.
- Israeli blockades of some or all the shores of Lebanon at various times during the Lebanese Civil War (1975–1990), the 1982 Lebanon War, and the 1982-2000 South Lebanon conflict - resumed during the 2006 Israel-Lebanon conflict.
Blockade running is the practice of delivering cargo, for example food, to an area in blockade. It has mainly been done by ships, called blockade runners
, across ports under naval blockade. Blockade runners were typically the fastest ships available, and often lightly armed and armoured.
However, in the modern age, it has also been done by aircraft, forming airbridges, such as over the Berlin blockade after World war II.