He led his unit into the Battle of Gettysburg. On July 3, 1863 they participated in the Pickett-Pettigrew-Trimble Charge and Gantt was shot in the face, losing his teeth. Colonel Gantt was transported back to Virginia, being on leave until returning to the field in 1864. Gantt commanded the 19th Virginia during the Battle of North Anna. After being hospitalized again he briefly commanded the brigade during the Bermuda Hundred Campaign and at Petersburg but apparently was hospitalized again in March 1965. He was paroled on June 1, 1865.