Military history of the United States during World War II Military history of the United States during World War II The military history of the United States in World War II covers the war against Germany, Italy, and Japan, starting with the 7 December 1941 attack on Pearl Harbor. During the first two years of World War II, the United States had maintained formal neutrality as made official in the Quarantine Speech delivered by U.S. President Franklin D. Roosevelt in 1937, while supplying Britain, the Soviet Union, and China with war materiel through the Lend-Lease Act which was signed into law on 11 March 1941, as well as deploying the
Asian and Pacific theatre of World War I on Germany. The German and Austro-Hungarian concessions in Tientsin and Hankow were occupied and their nationals detained. An even more serious plot was Germany's funding of the Constitutional Protection Movement, which geographically split China into two rival governments for eleven years. Asian and Pacific theatre of World War I The Asian and Pacific theatre of World War I consisted of various naval battles and the Allied conquest of German colonial possessions in the Pacific Ocean and China. The most significant military action was the careful and well-executed Siege of Tsingtao in what is now China, but smaller actions were also