During the Second World War, the United States emerged as a decisive force after entering the conflict in 1941 following Japan's attack on Pearl Harbor. In the European Theater, US forces played a key role in the Allied invasion of North Africa, Italy, and France, including the pivotal D-Day landings in Normandy and the final push into Germany. In the Pacific, the US adopted an island-hopping strategy, securing critical victories at Guadalcanal, Midway, Iwo Jima, and Okinawa, bringing the fight closer to Japan. The war concluded with the use of atomic bombs on Hiroshima and Nagasaki in August 1945, forcing Japan’s surrender. The US military's vast resources, innovative strategies, and collaboration with Allied nations were instrumental in the defeat of the Axis powers.