Educated at Winchester College, Hamilton-Gordon was commissioned into the Royal Artillery in 1880. His first military service was in the Second Anglo-Afghan War in 1880. Hamilton-Gordon later served in the Boer War taking part in actions at Ladysmith, Spion Kop, Vaal Kranz and Tugela Heights. He became Deputy Assistant Adjutant General for Intelligence in South Africa in early 1901. Arriving back in the United Kingdom, he briefly became an instructor at the School of Gunnery before he was appointed a Deputy Assistant Quarter-Master-General at Aldershot in October 1901.