Complex sentence: The Inspector General, Quartermaster General, Commissary General, and Adjutant General severed on the Secretary's staff, however the Army it's self under Secretary Henry Knox only consisted of 700 men.
Split into simpler sentences: The Inspector General, Quartermaster General, Commissary General, and Adjutant General served on the Secretary's staff. However, the Army itself under Secretary Henry Knox only consisted of 700 men.