The Asiatic-Pacific Theater was a major area of conflict during World War II, primarily involving the forces of the United States and its allies against the Empire of Japan. This theater encompassed a vast region, including the islands of the Pacific Ocean, parts of Southeast Asia, and the Philippines. Key battles included the Battle of Midway and the Battle of Guadalcanal, which were crucial in turning the tide against Japanese expansion. The campaign in the Asiatic-Pacific Theater began with Japan's surprise attack on Pearl Harbor in December 1941. Following this, the U.S. and its allies launched a series of military operations aimed at reclaiming territory and defeating Japanese forces. The theater concluded with Japan's surrender in September 1945, following the dropping of atomic bombs on Hiroshima and Nagasaki.