General Arnold retained personal command of the Twentieth Air Force – to avoid diversion of assets from the B-29 effort against Japan, particularly by Admiral Nimitz, who was given command authority over all efforts in the Central Pacific – with Brigadier General Haywood S. Hansell as chief of staff (and later commander of XXI Bomber Command). Tentative plans called for an operational force of 48 B-29 groups, numbering between 1,000 and 1,500 B-29s, to be deployed in four bomber commands (the XX BC of 4 groups in India-China, the XXI BC of 16 groups in the Marianas, the XXII BC of 24 groups in the Philippines and Okinawa, and the XXIII BC of 4 groups in the Aleutians).