August 21, 1959. U.S. President Dwight Eisenhower signed the proclamation that admitted the series of Pacific islands to the Union. Polynesian explorers are thought to have first settled on the island in the eighth century. The last reigning monarch, Queen Liliuokalani, was deposed by a group of U.S. Marines and American expatriates in 1893. Hawaii was officially annexed by the U.S. in 1898, following the Spanish-American War. A important region strategically and for the sugar industry, the volcanic islands became a territory in 1900. Following the bombing of Pearl Harbor in 1941, Hawaii became firmly established in the American identity.