After leaving New Zealand in December 1915 Alec Whitcombe joined the Royal Horse Artillery. He left for France on 22 July 1916 and served on the Western Front until wounded during the German attack at Bligny on 6 June 1918. He was moved to No 2 Casualty Clearing Station, Rouen, for an operation and then evacuated to England.

Following his recovery he was posted to Archangel to join the North Russia Expeditionary Force under General Ironside, fighting with the white Russians against the communists. He was awarded both the the Military Cross (British) and the Russian Order of St Anne for his services during the operations against Pocha, and providing training to the Pinega artillery forces.

He returned to England in June 1919 and was on leave until returning to New Zealand in December 1919.