Promoted to brigadier general of volunteers on April 16, 1864, Kautz led cavalry operations under the command of Maj. Gen. Benjamin Butler during Ulysses S. Grant's campaigns against Richmond and Petersburg between April and June 1864. His cavalry division was a part of the Army of the James and was forced to withdraw from its position at White's Tavern following an attack by parts of Confederate Lt. Gen. Richard H. Anderson's Corps. On December 12, 1864, President Abraham Lincoln nominated Kautz for appointment to the brevet grade of major general of volunteers, to rank from October 28, 1864, and the U.S. Senate confirmed the appointment on February 14, 1865. He was mustered out of the volunteers on January 15, 1866. On July 17, 1866, President Andrew Johnson nominated Kautz for appointment to the brevet grade of major general, U.S. Army, to rank from March 13, 1865, and the U.S. Senate confirmed the appointment on July 23, 1866.