Macdonald was finally sent to the front lines in France in May 1918 as a lieutenant in Nova Scotia's 25th battalion. He participated in heavy fighting and on one occasion led his entire company because all of the other officers had been wounded or killed. Macdonald felt fortunate to have been spared, but his luck ran out in Belgium when he was hit in the neck by a German sniper's bullet on November 7, 1918, just four days before the Armistice.