At the outbreak of war, Lieutenant Colonel Tuxford attested for overseas service with the Canadian Expeditionary Force and was appointed to command the 5th (Western Cavalry) Battalion at Camp Valcartier. He took his unit overseas and led it during the Second Battle of Ypres in April 1915, as well at the Battle of Festubert. In March 1916 he was promoted brigadier general and appointed to the command of the 3rd Canadian Infantry Brigade, which he led during the battles of Mount Sorrel, the Somme, Courcelette, Vimy Ridge, Hill 70, Amiens, Arras, and Cambrai. Following the armistice in November 1918, his formation participated in the march to the Rhine and served as part of the occupation force in Germany until all Canadian units were returned home.