Taiwan held strategic wartime importance as Imperial Japanese military campaigns first expanded and then contracted over the course of World War II. The Imperial Japanese Navy operated heavily from Taiwanese ports. The "South Strike Group" was based at the Taihoku Imperial University in Taipei. Important Japanese military bases and industrial centres throughout Taiwan, such as Kaohsiung and Keelung, became targets of heavy raids by American bombers. In October 1944b the Formosa Air Battle was fought between American carriers and Japanese forces based in Taiwan.