Hiroshima is the capital of Hiroshima Prefecture, and the largest city in the Chgoku region of western Honshu, the largest island of Japan. It is best known as the first city in history to be targeted by a nuclear weapon when the United States Army Air Forces (USAAF) dropped an atomic bomb on it at 8:15 A.M. on August 6, 1945, near the end of World War II. Its name means 'Wide Island'. Hiroshima gained city status on April 1, 1889. On April 1, 1980, Hiroshima became a designated city. The city's current mayor since April 2011 is Kazumi Matsui. Hiroshima was founded on the river delta coastline of the Seto Inland Sea in 1589 by the powerful warlord Mri Terumoto, who made it his capital after leaving Koriyama Castle in Aki Province. Hiroshima Castle was quickly built, and Terumoto moved in, in 1593. Terumoto was on the losing side at the Battle of Sekigahara.