On 8 March 1945 the regiment moved with the I Canadian Corps to North-West Europe as part of Operation Goldflake, where it fought until the end of the war.

In June 1941, the regiment sailed from Halifax on the Pasteur, arriving in Greenock, Scotland, on 1 July, and headed south to Headley Down, England.

On 21 December 1941, the regiment moved to Brighton, alternating between there and Shermanbury park in operational roles in the defence of the English coast.

The unit fought with distinction in several theatres during the war, beginning with the Allied invasion of Sicily in July 1943, through the Italian Campaign seeing action in the fierce Liri Valley, Monte Cassino, and on to Ortona.

In 1945, the unit entered the Northwest European theatre where it fought with distinction in the Dutch Campaign winning honours at Arnhem.

Some of these actual tanks can be seen as monuments or gate guards at [CFB Kingston] and the former Denison Armoury on Dufferin Street in Toronto.

During many of the subsequent years, the regiment maintained a wheeled armoured reconnaissance squadron (later downsized to an RHQ recce troop) employing the Iltis jeep.

With the retirement of the Cougar in the 2004, the regiment was again re-designated an armoured reconnaissance unit, briefly employing and conducting trials on all terrain vehicles.

A significant number of the regiment's soldiers have volunteered for active duty with NATO in Germany, United Nations missions in Cyprus, Bosnia, the Golan Heights, Cambodia, the former Yugoslavia and, most recently, the NATO-led engagement with ISAF in Afghanistan.

[3] A regimental "challenge" coin was issued in late 2009 by LCol R Brown and CWO DJ Munroe to the members and officers serving, as a remembrance of those Ontarios who have fallen in the line of duty.

A complete historical list[4] of the unit's key appointments is maintained at the Regimental Museum's official website.

Lt (N) Bill Askew, a naval veteran of World War II and officer with the 1913 Ontario Regiment Cadet Corps refused to let the band wither.

In September 1983, a small group of Welsh officers and soldiers were on parade in Oshawa on the occasion of the Ontarios’ change of command.