231st Battalion, CEF Seaforth Highlanders of Canada. This photo is most likely one of the pictures from the 231st Battalion Souvenir Book, 1917. The 231st Battalion, CEF was a unit in the Canadian Expeditionary Force during the First World War. Based in Vancouver, the unit began recruiting in early 1916. After sailing to England in April 1917, the battalion was absorbed into the 24th Reserve Battalion on April 22, 1917. The 231st Battalion, CEF had one Officer Commanding: Lieut-Col. Francis E. Leach.