Before revision: World War II 325px| Convoy routes in the Atlantic Ocean during 1941 Atlantic The British adopted a convoy system, initially voluntary and later compulsory for almost all merchant ships, the moment that World War II was declared.
After revision: World War II Atlantic Convoy routes in the Ocean during 1941 Atlantic The British adopted a convoy system, initially voluntary and later compulsory for almost all merchant ships, the moment that World War II was declared.