The U.S. general who led Allied forces in Europe during World War II was Dwight D. Eisenhower. As the Supreme Commander of the Allied Expeditionary Forces, Eisenhower was pivotal in planning and executing significant operations, including the D-Day invasion of Normandy in 1944. His leadership, diplomatic skills, and strategic vision were crucial in coordinating a successful campaign against the Axis powers, eventually leading to the liberation of Western Europe and the defeat of Nazi Germany.