On 20 March 1945, the Imperial General Headquarters commenced Operation Ten-Go to defend Okinawa against the impending Allied invasion. Air groups mobilized included Carrier Division 5, 1st Mobile Land-based Air Fleet (Kyushu, commanded by Vice Admiral Matome Ugaki), 5th Land-based Air Fleet (Formosa), and the Imperial Japanese Army 6th Aviation Army's 8th Flying Division (Formosa, commanded by Lieutenant General Kenji Yamamoto). These forces undertook preparations for Operation Kikusui (which was an Imperial Japanese Navy code name; the Imperial Japanese Army referred to it as the "total air assault"), and stationed over 3,000 various combat aircraft in Kyushu.