Blockade

A blockading power can seek to cut off all maritime transport from and to the blockaded country; although stopping all land transport to and from an area may also be considered a blockade. Blockades restrict the trading rights of neutrals, who must submit for inspection for contraband, which the blockading power may define narrowly or broadly, sometimes including food and medicine. In the 20th century, air power has also been used to enhance the effectiveness of the blockade by halting air traffic within the blockaded airspace.


Close patrol of hostile ports, in order to prevent naval forces from putting to sea, is also referred to as a blockade. When coastal cities or fortresses were besieged from the landward side, the besiegers would often blockade the seaward side as well. Most recently, blockades have sometimes included cutting off electronic communications by jamming radio signals and severing undersea cables. Blockades often result in the starvation of the civilian population, notably during the blockade of Germany during World War I and the blockade of Biafra during the Nigerian Civil War.^[1]


According to modern international law, blockades are an act of war.^[2] They are illegal as part of a war of aggression^[3] or when used against a civilian population, instead of a military target.^[4] In such case, they are a war crime and potentially a crime against humanity.^[5][6]

History[edit]

Although primitive naval blockades had been in use for millennia, the first successful attempts at establishing a full naval blockade were made by the British Royal Navy during the Seven Years' War (1754–1763) against France.^[7] Following the British naval victory at Quiberon Bay, which ended any immediate threat of a major invasion of Britain,^[8] Britain established a close blockade on the French coast. This starved French ports of commerce, weakening France's economy. Admiral Edward Hawke took command of the blockading fleet off Brest and extended the blockade to cover the entire French Atlantic coast from Dunkirk to Bordeaux, and also to Marseilles on France's Mediterranean coast.^[9]


The strategic importance of blockade was shown during the French Revolutionary Wars and Napoleonic Wars, when the Royal Navy successfully blockaded France, leading to major economic disruptions. The Union blockade of southern ports was a major factor in the American Civil War. During World War I, the Allies blockaded the Central Powers, depriving them of food and other strategic materials. Germany's attempted U-boat blockade caused some shortages in Britain, but ultimately failed. This outcome was repeated in World War II.


Naval strategic thinkers, such as Sir Julian Corbett and Alfred Thayer Mahan, wrote that naval conflicts were won primarily by decisive battles, but also by blockade.^[10]