Battle of the Atlantic

Battle context

The Battle of the Atlantic was the longest continuous military campaign of World War II, running from 1939 to the defeat of Nazi Germany in 1945. At its core was a struggle between the Allied naval blockade of Germany, announced the day after the declaration of war, and Germany's counterblockade. The campaign determined whether Allied supply lines across the Atlantic could be maintained against sustained German interdiction. Its peak stretched from mid-1940 to the end of 1943, a period in which the outcome of the broader war remained contingent on control of Atlantic sea lanes. British casualties reached 36,200 and German losses 30,000, reflecting the sustained attrition of a campaign fought over years rather than days. Allied success in maintaining the blockade and protecting transatlantic shipping underpinned the material capacity to prosecute the war in Europe.