The Supermarine Spitfire Mk. IX replaced the Mk. V in June 1942 and continued in service until the end of WWII. W. Duncan Smith began his military service with the 7 Operational Training Unit (OTU) before being posted to the No. 611 Squadron and in June 1941 received the DFC. During the Dieppe raid, Duncan Smith was shot down in his Spitfire Mk. IX but was recovered from the English Channel. Eventually Duncan-Smith took charge of the 324 Wing in the Mediterranean. Duncan-Smith flew Spitfire IX JK650 'DS' as a Luqa Wing OC, and later flew Spitfire IX MH884 'DS' from Corsica to Ravenna as Group Capt. and OC of 324 Wing 1944-45. He is credited with 17 aircraft shot down, 2 shared shot down, 6 probables, 2 shared probables and 8 damaged in aerial combat.