 Groves was also a colonel, and ranked below Marshall on the permanent list, although Groves was promoted to brigadier general before assuming command on 23 September.According to Nichols, Groves and Marshall "disagreed in a major way on how to handle personnel", and Nichols "did witness several confrontations".Major General Wilhelm D. Styer, the Chief of Staff of the Army Service Forces, decided that Marshall would be replaced by Nichols.