Which battle was the last before the invasion of mainland?

The last significant battle before the invasion of mainland Japan was the Battle of Okinawa, fought from April to June 1945. This brutal and intense conflict resulted in heavy casualties for both Allied and Japanese forces, marking a crucial step in the Pacific Theater of World War II. The outcome paved the way for the eventual plans to invade Japan's home islands, although the use of atomic bombs later led to Japan's surrender before such an invasion occurred.