Dundas was called up early in the
Second World War, serving with
No. 616 Squadron flying Spitfires. He was shot down on 22 August 1940 and wounded during the
Battle of Britain, but returned to his squadron in September. His brother John, a 12-kill ace with No. 609 Squadron, was killed in action in November 1940 after shooting down
Helmut Wick, the top–scoring German ace at the time. Dundas was promoted to flying officer (
war substantive) on 2 October. In early 1941, No. 616 Squadron was a part of the
RAF Tangmere Wing, under the command of Wing Commander
Douglas Bader. Through the summer of 1941 Dundas frequently flew with Bader's section, gradually building his reputation as a competent fighter pilot and tactician. By now an acting flight lieutenant, he was awarded a
Distinguished Flying Cross on 5 August 1941. The citation read: In September 1941, Dundas was posted as an instructor to No. 59 Operational Training Unit, but his scruffiness and unruly pet dog did not endear him to the commanding officer, Group Captain
Stanley Vincent, and he was transferred promptly as a flight commander with No. 610 Squadron. Promoted to flight lieutenant (war substantive) on 2 October, he was subsequently promoted to acting squadron leader and posted as commanding officer of
No. 56 Squadron RAF in December, the first to be equipped with the
Hawker Typhoon. He was
mentioned in despatches on 1 January 1943, and was promoted to squadron leader (war substantive) on 11 February. Posted to the Mediterranean in 1943, he led No. 324 (Spitfire) Wing from
Malta and through Italy. He was awarded his first
Distinguished Service Order (DSO) on 3 March 1944. In June, Dundas was promoted to the acting rank of group captain at the age of only 23. He led No. 244 Wing from June 1944, and was promoted to wing commander (war substantive) on 11 May 1945. His war time score was 4 enemy aircraft destroyed, 6 shared destroyed, 2 shared probables, and 2 and 1 shared damaged. ==Post-war career and later life==