 In July 1864, Ricketts and his command, numbering only 3,350 men, were hurried north to oppose Jubal Early's attack on Washington, D.C. Ricketts fought at the Battle of Monocacy under Major General Lew Wallace, suffering the heaviest losses while holding the Union left flank.For his service there, on December 12, 1864, President Lincoln nominated Ricketts for appointment to the brevet grade of major general of volunteers, to rank from August 1, 1864, and the U.S. Senate confirmed the appointment on February 14, 1865.Ricketts was engaged in Philip Sheridan's Shenandoah Valley Campaign.