Rule passed from Spain to Germany in 1899. Japan took over during World War I. Japan ruled as Saipan under a League of Nations Mandate until 1935, when Japan left the League. Then Japan annexed Saipan and the nearby islands of Tinian and Rota.
Sugar and fishing industries developed under the Japanese. Japanese civilians grew to around 24,000 while the local population remained around 3,200. By the beginning of World War II, 29,692 military personnel were garrisoned on the island.