In mid-1943, the 353rd FG was initially stationed at RAF Goxhill in Lincolnshire, England, before moving to RAF Metfield in Suffolk, England in August 1943. After switching its base to Metfield, the 353rd FG flew its first combat mission. On September 23, 1943, Duncan scored his first victory, a Fw 190 over Nantes. He began flying frequent escort missions and destroyed a Fw 190 and Bf 109 on November 11, for which he received the Distinguished Service Cross. He was made full Colonel in November 1944.
