Returning from military service in the Pacific Northwest in 1861, Kautz became a captain in the Sixth U.S. Cavalry. He served in the Peninsula campaign and the Seven Days' campaign before he was sent to the Kansas-Missouri border. In late 1863 he was transferred back to the East as the cavalry commander for the Army of the James in the campaigns against Richmond and Petersburg. In 1864, instead of receiving a promotion to major general, he received command of a black infantry division, among the first to occupy Richmond. He mustered out in 1866 but returned to service on the frontier.
