Complex sentence: He later served in China as chief of staff for General Claire Chennault of the China Air Task Force--precursor of the Fourteenth Air Force--then from 1943 to 1945 in the Southwest Pacific as chief of staff for the Fifth Air Force's Bomber Command.
Split into simpler sentences: He later served in China as chief of staff for General Claire Chennault of the China Air Task Force, which was the precursor of the Fourteenth Air Force. He served then from 1943 to 1945 in the Southwest Pacific as chief of staff for the Fifth Air Force's Bomber Command.