Arriving on the Western Front with the substantive rank of captain, he led a "most brilliant" raid on German trenches near Fleurbaix, and although severely wounded in the head, stuck to his command until the operation was successfully completed. For his actions he was appointed a Companion of the Distinguished Service Order (DSO), the second highest award for gallantry by officers. When he returned from hospital, he was promoted to major, and was in temporary command of his battalion during the Second Battle of Bullecourt in May 1917. In July, he was promoted to lieutenant colonel and appointed to command the 10th Battalion. He led that unit during the Battle of the Menin Road Ridge in September and was appointed a Companion of the Order of St Michael and St George in June 1918. Perhaps his greatest achievement was the capture of Merris in July, for which he was awarded a bar to his DSO, again for gallantry. He continued to skilfully lead his battalion throughout the Hundred Days Offensive and up to the Armistice of 11 November. During the war, in addition to decorations already mentioned, he was awarded the French Croix de guerre and was mentioned in despatches five times.