It was first raised in the 1860s as an infantry regiment, and contributed heavily to the 91st Battalion (Elgin), CEF.

[1][2] The regiment mobilized the Elgin Regiment, Canadian Active Service Force (CASF) on 24 May 1940.

The CASF regiment was converted to armour and redesignated the 25th Armoured Regiment (The Elgin Regiment), Canadian Armoured Corps on 26 January 1942.

[3] The regiment again became an armoured unit during the Cold War.

In 1997, the regiment was converted from armour to combat engineers as the 31 Combat Engineer Regiment (The Elgins).