Greenshields was called to full time service on the outbreak of war and, having qualified as a pilot, he was attached to the RAF in June 1940 and sent to the Operational Training Unit at Hawarden to convert to Spitfires. He joined No 266 Squadron at the beginning of July.
He probably destroyed a Bf 110, as well as damaging two, on 12 August, and destroyed a Bf 109 south east of Dover on the 15th. Next day he failed to return from a combat with Bf 109s which he had pursued out over the Channel. He was shot down and killed by Leutnant Müller-Duhe of JG 26. The Spitfire, N 3240, crashed in the suburbs of Calais at the side of the St Omer canal. Local people were convinced that Greenshields had remained at the controls of the aircraft to steer it away from buildings and streets. The Germans mounted a guard as his body was removed.
Henry Greenshields was buried in Calais Southern Cemetery next to Flying Officer Laurence Pyman of No 65 Squadron, who was killed on the same day. The pair were accorded German military honours.
