The 121st (Western Irish) Battalion, CEF was a unit in the Canadian Expeditionary Force during the First World War. Based in New Westminster, British Columbia, the unit was authorized on 22 December 1915^[1] and began recruiting in that city. After sailing to England on RMS Empress of Britain^[2] in August 1916, the battalion was absorbed into the 16th Reserve Battalion on January 10, 1917. The 121st (Western Irish) Battalion, CEF had one Officer Commanding: Lieutenant-Colonel Archibald Woodbury McLelan.^[3]

The 121st Battalion is perpetuated by The British Columbia Regiment (Duke of Connaught's Own).^[4] The perpetuation has been passed down through the following units as a result of reorganizations and amalgamations:

• 1920–1936: 1st Battalion (121st Battalion, CEF), The Irish Fusiliers of Canada
• 1936–1946: Irish Fusiliers (Vancouver Regiment)
• 1946–1958: 65th Light Anti-Aircraft Regiment (Irish Fusiliers), RCA
• 1958–2002: The Irish Fusiliers of Canada (The Vancouver Regiment)
• 2002–present: The British Columbia Regiment (Duke of Connaught's Own)

• Meek, John F. Over the Top! The Canadian Infantry in the First World War. Orangeville, Ont.: The Author, 1971.