In September 1914, following the outbreak of the First World War, Kerr enlisted in the
3rd (Toronto) Battalion of the
Canadian Expeditionary Force (CEF). He embarked for Britain the next month and, with his battalion part of
1st Canadian Infantry Brigade,
1st Canadian Division, arrived in France on the Western Front in February 1915 after a period of training. By this stage, he had been promoted to
corporal. Kerr served in the
Ypres sector with his battalion for much of 1916, and in June, was awarded the
Military Medal (MM) for his actions during the
Battle of Mont Sorrel. He was wounded the next month and the severity of his injuries warranted him being sent to England for medical treatment. He did not return to his unit for several months but when he did, it was as a
lieutenant; he had been commissioned while serving with a reserve battalion back in England. On 8 August 1918, the opening day of the
Battle of Amiens, Kerr led a
platoon of infantry in closing a gap in the Allied line and captured a battery of field guns. Advancing further forward, he and his men destroyed several machine-gun posts before reaching their objective for the day. Wounded, he remained with his platoon for two days before seeking medical treatment. He was later awarded the
Military Cross (MC) for his endeavours. Learning of the forthcoming
offensive on the Drocourt-Quéant Line, for which his battalion was scheduled to participate on 2 September 1918, he discharged himself from medical care and re-joined his platoon. He was again instrumental in attack, and his leadership was recognised with an award of a
bar to his MC. On 27 September 1918, Kerr was commanding a support
company at Bourlon Wood, during the
Battle of the Canal du Nord (a part of
Canada's Hundred Days). The advance of the 2nd and 3rd Battalions of the 1st Brigade was affected by heavy machine-gun fire from a nearby railway embankment. Under his command, Kerr's company dealt with the holdup. He later made a solo foray, ahead of his company, during which four machine-guns were destroyed and 31 prisoners taken. For this, Kerr was awarded the Victoria Cross (VC) for his actions. The citation for his VC read: Kerr's VC was
gazetted on 4 January 1919, which was a month after his MC was announced in the London Gazette. The bar to his MC was gazetted on 1 February 1919. He was presented with his VC, as well as his MC and bar, in a ceremony at
Buckingham Palace on 20 May 1919. ==Later life==