In the Second Boer War he was placed at the head of a division with the rank of lieutenant general. Gatacre was the commanding general of the Imperial forces at the Battle of Stormberg in which 135 men were killed and 696 captured during an ambush.
Though he worked them hard, Gatacre's men loved him and called him "General Backacher." Lady Gatacre wrote his Life (London, 1910).