As unrest grew in Europe, the United States did not want to get involved in another European war. The young nation was dealing with its own economic troubles and took many steps to try to avoid joining the war overseas. With the Neutrality Act of 1935, the banned loans to belligerents in 1936 and the "cash-and-carry" requirement of 1937, the United States had made its intentions clear.

As the situation grew worse in Europe, the United States implemented the Lend-Lease Act in 1941, this allowed the United States to support Allies fighting against Germany, Italy and Japan. "The implementation of lend-lease marked the unofficial entrance of the United States into the European war" (Henretta, 2012, Pg.730). The official entrance came after the attack on Pearl Harbor by Japanese bombers on December 7, 1941. With approximately 2,400 dead, multiple ships and hundreds of airplanes destroyed, President Roosevelt asked Congress to go to war.

The first major turning point in the European Theatre was in the winter of 1942. "In the epic Battle of Stalingrad, Soviet forces not only decisively halted the German advance, but allowed the Russian army to push westward (Henretta, 2012, Pg. 745). Next came D-Day on June 6, 1944, American, British and Canadian soldiers assaulted the beaches of Normandy, France. This would be the anchor point that allowed millions of soldiers and supplies to be funneled into Europe. The final push to get the Germans out of France came at the Battle of the Bulge, with this victory Allied troops were able to attack Germany from the West and Soviet troops from the East. This resulted in the formal surrender of Germany when Hitler committed suicide on May 7, 1945.

In the Pacific, The Battle of the Coral Sea was a victory that stopped the Japanese from assaulting Australia. "Then, in June, at the Battle of Midway Island, the American navy inflicted serious damage on the Japanese fleet" (Henretta, 2012, Pg. 750). The last major battle occurred in the Philippines, the Battle of Leyte Gulf. When the fighting was done and the waters calmed, the Japanese had lost almost the entirety of their fleet. With this victory in the Pacific the United States and was finally attack Japan at their homeland, leading the Atomic bombing of Hiroshima and Nagasaki Japan. The Japanese government surrendered officially on September 2, 1945.