The 20th Battalion (Central Ontario), CEF was a unit of the First World War Canadian Expeditionary Force.

[1][2] The battalion was composed of volunteers from militia units in central Ontario.

[4][5] Notable actions include the Somme, Vimy Ridge, Hill 70, Passchendaele, Amiens, the advance along the Scarpe, Canal du Nord, Canal de l'Escaut and the advance to Mons in the Last Hundred Days.

4,310 officers and men served in the 20th Battalion during the war altogether.

Ottawa stopped counting the deaths to old injuries, mental trauma and exposure to gas as war deaths in 1922 while the nominal roll of the 20th (privately held after the battalion disbanded) attributed these to the war until 1928.