Pole-Carew was commissioned into the Coldstream Guards in 1869. He served as a staff officer with Lord Roberts in the Second Anglo-Afghan War in 1878 and again served with him during the Second Boer War 1899–1902. He was promoted to the substantive rank of colonel on 27 November 1899, and at the same time appointed in command of the 9th Brigade with the local rank of major-general. As such he was in command of the brigade during the Battle of Modder River on 28 November 1899. In February 1900 he was appointed in command of the Guards Brigade, shortly before the Relief of Kimberley. He later commanded the 11th Division of the South Africa Field Force, before becoming General Officer Commanding 8th Division in Southern Ireland in 1903.