When the Second World War broke out in September 1939, Gorman was attending the Imperial Service College in Windsor. He then attended Portora Royal School, before joining the British Army. Gorman was commissioned as a second lieutenant into the Irish Guards on 5 December 1942. He was posted to the regiment's 2nd Battalion, which formed part of the 5th Guards Armoured Brigade of Major General Allan Adair's Guards Armoured Division, which, in late June 1944, landed in Normandy as part of Operation Overlord, a few weeks after D-Day landings.