At First Bull Run, he was wounded and captured, but later exchanged. He fought at Second Bull Run and Antietam, where he was badly injured when his horse fell on him. While recuperating, he served on the Fitz John Porter court-martial, a highly political case, where his loyalties are believed to have cost him promotion. Later he commanded a division in the Overland campaign, and a corps in the Shenandoah Valley Campaign under Sheridan, where he received a chest wound at Cedar Creek that disabled him for life.