The primary naval battle fought in the Pacific during World War II was the Battle of Midway, which took place in June 1942. This pivotal battle marked a turning point in the Pacific Theater, as U.S. naval forces, having broken Japanese codes, successfully ambushed and defeated a larger Japanese fleet. The U.S. sank four Japanese aircraft carriers, decisively shifting the balance of naval power in the Pacific. Midway demonstrated the effectiveness of aircraft carriers and naval aviation, fundamentally changing naval warfare. The victory boosted American morale and set the stage for subsequent offensive operations against Japan, leading eventually to the Allied victory in the Pacific.