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.
Late on the morning of 20 November 1917, his battalion of twelve Mark IV tanks, entered the town of Masnières.
As part of the mission to clear pockets of resistance near Cambrai, on November 20, 1917, the regiment was engaged in an assault on the French village of Masnieres when a German shell exploded killing seven, including Shiwak.