General Dwight D. Eisenhower oversaw World War II as the Supreme Commander of the Allied Expeditionary Forces. He played a crucial role in planning and executing the Invasion of Normandy, also known as D-Day, which marked a turning point in the war. Eisenhower's strategic leadership and ability to coordinate between various Allied nations were pivotal in defeating Nazi Germany and ending the conflict in Europe. His military success later paved the way for his presidency and established his legacy in American history.