Chennault was recalled to active duty in the USAAF on 15 April 1942 in the grade of Major General. Chennault was told that he would have to be satisfied with command a "China Air Task Force" of fighters and bombers as part of the Tenth Air Force. Its mission was to defend the aerial supply operation over the Himalayan mountains between India and China – nicknamed the Hump – and to provide air support for Chinese ground forces. Bissell had been promoted to brigadier general with one day's seniority to Chennault in order to command all American air units in China as Stillwell's Air Commander (in August 1942 he became commanding general of the Tenth Air Force). Friction developed when Chennault and the Chinese government were disturbed by the possibility that Chennault would no longer control combat operations in China. However, when Tenth Air Force commanding general Lewis Brereton was transferred to Egypt on 26 June, Stillwell used the occasion to issue an announcement that Chennault would continue to command all air operations in China.