A blockade is the act of actively preventing a country or region from receiving or sending out food, supplies, weapons, or communications, and sometimes people, by military force.
A blockade differs from an embargo or sanction, which are legal barriers to trade rather than physical barriers. It is also distinct from a siege in that a blockade is usually directed at an entire country or region, rather than a fortress or city and the objective may not always be to conquer the area.
C47s unloading at Tempelhof Airport in Berlin, part of the airlift of supplies which broke the Soviet Union's 1948 land blockade of West Berlin
In World War II, German U-boats attempted to stop ships carrying food, supplies and matériel from reaching the United Kingdom, an example of a distant blockade.
President Kennedy and his advisors discuss the Cuban Missile Crisis. Part of the US response to Soviet missiles being placed in Cuba was a naval blockade of the island.
A Northern cartoonist ridicules the Union's initial attempts to blockade ports of the Confederacy in the American Civil War
A siege is a military blockade of a city, or fortress, with the intent of conquering by attrition, or by well-prepared assault. Siege warfare is a form of constant, low-intensity conflict characterized by one party holding a strong, static, defensive position. Consequently, an opportunity for negotiation between combatants is common, as proximity and fluctuating advantage can encourage diplomacy.
Depiction of the siege of Lisbon, 1147
Picture of the siege of Rancagua during the Chilean War of Independence
Assyrians using siege ladders in a relief of attack on an enemy town during the reign of Tiglath-Pileser III 720–738 BCE from his palace at Kalhu (Nimrud)
The Egyptian siege of Dapur in the 13th century BC, from Ramesseum, Thebes