Complex sentence: From August 20,1861, to March 1864, Williams was assistant adjutant general of the Army of the Potomac, responsible for the routine drafting of orders, correspondence, and reports.
Split into simpler sentences: From August 20,1861, to March of 1864, Williams was assistant adjutant general of the Army of the Potomac. As assistant adjutant general, Williams was responsible for the routine drafting of orders, correspondence and reports.