World War 2 And The American Navy The American Navy joined World War II in 1941. Actually they had already started fighting unofficially in 1939. The American Navy did everything that they could to stay out of this treacherous world war. America even gave away supplies such as warships, food, and medicine. America was extremely supportive of the war as long as they didn’t have to get in the trenches of it. They supported the British forces by fulfilling much needed supplies. America gave the British Parliament 7 billion dollars’ worth of American accouterments in 1942. Life on board these gr