Strachan was 33 years of age, and serving in the First World War with the Canadian Cavalry Brigade as a lieutenant in The Fort Garry Horse, when he performed the action for which he was awarded the VC.
During the Battle of Cambrai on 20 November 1917 at Masnières, France, Lieutenant Strachan took command of a mounted squadron of Garrys when the squadron leader, approaching the German front line at a gallop, was killed.