 At the Battle of Chancellorsville he commanded the 1st Brigade, 1st Division, III Corps.Upon the mortal wounding of Amiel W. Whipple, Graham assumed command of the 3rd Division, III Corps on the last day of the battle, May 4, 1863, through June 20, 1863.He returned to command the 1st Brigade, 1st Division in June during the Gettysburg Campaign.