Naval Base Hawaii was a number of United States Navy bases in the Territory of Hawaii during World War II. At the start of the war, much of the Hawaiian Islands was converted from tourism to a United States Armed Forces base. With the loss of US Naval Base Philippines in Philippines campaign of 1941 and 1942, Hawaii became the US Navy's main base for the early part of the island-hopping Pacific War against Empire of Japan. Naval Station Pearl Harbor was founded in 1899 with the annexation of Hawaii.