The Imperial Japanese Navy's Combined Fleet was the main naval force of Japan during the early 20th century, particularly active during World War II. It was established to unify Japan's naval operations and included various types of ships, such as battleships, aircraft carriers, and submarines. The fleet played a crucial role in Japan's military strategy and was involved in significant battles, including the Battle of Midway. The Combined Fleet was known for its advanced naval tactics and technology, which initially gave Japan an advantage in the Pacific theater. However, as the war progressed, the fleet faced increasing challenges from the United States Navy and ultimately suffered heavy losses, leading to its decline by the end of the war.