In December 1863 Williams was assigned command of Roseville, Arkansas, in the District of the Frontier, Department of the Missouri, and he participated in the Camden Expedition in southern and central Arkansas from March 23 to May 2, 1864. He then exercised brigade command at various times in the District of the Frontier and in the VII Corps for the remainder of 1864 through the fall of 1865. Williams also fought at the Battle of Fort Smith in western Arkansas on July 31, 1864.