Donald's father served as an officer in the Royal Field Artillery during the Great War.
At the commencement of the Second World War, 55 Squadron, Royal Air Force was based in Egypt, later moving to Libya. Equipped with Bristol Blenheim's the squadron flew in shipping patrols and later in the major North African campaigns.
After being re-equipped with Baltimore's in 1942, the squadron distinguished itself at the 'Battle of El Alamein,' where it flew 352 operational sorties in the first ten days, it being more than any other Desert Air Force light bomber squadron in the same period.
Following the success of the war in North Africa, eventually Donald's squadron moved into Sicily and Italy, and converted to Douglas Boston's during the last few months of the war.