After arriving overseas he joined No. 412 Squadron, Fighter Command, flying Spitfires from Digby, Lincolnshire. After several sorties over France, Smith was posted to Malta, arriving there on July 15, 1942, when he joined 126 RAF Squadron. On July 18 he shared in the destruction of a Junkers 88 twin engine bomber with another pilot - his own brother Jerry Smith. After more victories with his brother, on 10 August, 1942, his brother Jerry, was posted missing, presumed killed in action.

By early October, when a new German blitzkrieg against Malta was in process, Flight Lieutenant Smith had shot down a total of five enemy aircraft. On October 15, his aircraft was so badly shot up he was forced to bail out. He scored his sixth and final victory over Malta on October 28. Then a case of jaundice hospitalized him and he was posted back to England.

After a stint as an Operational Training Unit instructor, he returned to Canada for leave. Then in December 1943, Smith joined 401 Squadron RCAF at Biggin Hill in Kent, flying fighter sweeps and bomber escort missions over the continent.

In March 1944, Smith was appointed a flight commander with his old unit, 412 squadron. At this time the Canadian fighter squadrons were engaged in dive-bombing missions in preparation for the Normandy invasion. Following the June 6^th D-Day invasion, the unit moved to a strip at Beny-sur-Mer in France, where on July 7, 1944, he shot down a Focke-Wulf 190. In early September the squadron moved to Brussels.

When the Arnhem airborne landing began, his unit covered the vital Nijmegen bridge. Between September 24 and 27, Squadron Leader Smith shot down six enemy planes, an achievement that earned him a second Distinguished Flying Cross (DFC). At this time he became commanding officer of 401 Squadron. Following a victory over an ME 262 jet, Smith ended his second tour having flown a total of 225 missions and scoring 13 and one fifth enemy aircraft destroyed.