Congress passes a series of Neutrality Acts to prevent involvement in European and Asian conflicts.
The US begins supplying weapons and provisions to Great Britain and later other allies, without directly entering the war.
Japan attacks the American naval base in Hawaii, immediately drawing the US into the war.
Roosevelt signs an executive order that leads to the forced internment of tens of thousands of Japanese Americans.
The American navy defeats the Japanese fleet in a decisive naval battle near Midway Atoll.
Allied troops, with a large American contingent, land on the beaches of Normandy to liberate Western Europe.
Roosevelt, Churchill and Stalin meet to discuss the post-war order in Europe.
President Franklin D. Roosevelt dies unexpectedly, after which Vice President Harry Truman takes over the presidency.
The United States drops atomic bombs on the Japanese cities of Hiroshima and Nagasaki, with devastating consequences.
Japan signs the official surrender, bringing the Second World War to an end worldwide.
President Roosevelt convinces Congress that America must become the 'arsenal of democracy'. The act makes it possible to lease materiel instead of selling it, which relieves the fragile British economy. This is a crucial step away from neutrality, although American troops are not yet actively fighting.