Who was the leader of the United States during World War II?

Franklin Delano Roosevelt served as the President of the United States from 1933 until his death in 1945 including during the critical years of World War II. He led the nation through the Great Depression and the global conflict with strategic policies and strong alliances. Roosevelt championed the Lend-Lease program aiding Allied nations before America formally entered the war. His leadership was instrumental in organizing military mobilization industrial production and diplomatic cooperation among Allies. Under his guidance the US emerged as a leading global power shaping the post-war world order through initiatives like the United Nations.