Answer:
Lend-Lease and Military Aid to the Allies in the Early Years of World War II. During World War II, the United States began to provide significant military supplies and other assistance to the Allies in September 1940, even though the United States did not enter the war until December 1941.
In response to the U-Boat attacks, Allied merchant ships sailed in groups, called convoys, escorted by warships. ... By the end of 1917, 3,170 Allied and neutral ships, totaling nearly six million tons, were sunk.
The Allies' defence against, and eventual victory over, the U-boats in the Battle of the Atlantic was based on three main factors: the convoy system, in which merchant ships were herded across the North Atlantic and elsewhere in formations of up to 60 ships, protected, as far as possible, by naval escorts
