McComb was wounded in several battles, including Gaines' Mill, Antietam, and Chancellorsville. In August 1863, he took command of Brig. Gen. Cadmus M. Wilcox's old Alabama brigade. He commanded this unit through the Overland Campaign and on through the Siege of Petersburg. He was finally promoted to brigadier general on January 20, 1865. He was paroled at Appomattox Court House.