Donald Harris initially served in the Ox and Bucks Light Infantry and  volunteered for service with The Parachute Regiment while still 18 years of age.He qualified as a military parachutist on Course 111 which ran at RAF Ringway from 10 to 21 April 1944.

Donald was posted to 8th Parachute Battalion shortly before the start of the campaigns to liberate North West Europe from occupation by German forces, and subsequently rose to the rank of Sergeant.