During the Fenian Raid of 1866, when the Irish extremists attempted to influence British policy by attacking Canada, the regiment was called to active duty, both to Niagara and later to Cornwall.

Very quickly a contingent of 80 men was formed under Captain George T. Richardson, (for whom George Richardson Stadium in Kingston is named—he became the PWOR’s first officer fatality) and sent to the 2nd (Eastern Ontario Regiment) Battalion Canadian Expeditionary Force (CEF), of the 1st Canadian Division, which was part of Canada’s First Contingent.

At the same time, the 21st Battalion, CEF was formed in Kingston, under the commanding officer of the PWOR, Lieutenant-Colonel St Pierre Hughes.

The mascot of the Princess of Wales' Own Regiment during the Great War, a white goat named Nan, retired to the Royal Military College of Canada stables in 1918.

She was buried in the Cataraqui Cemetery[4] In 1920, in the post war re-organization of the Militia, the 14th Battalion Rifles was re-designated as a line infantry regiment so that it could carry the battle honours and colours of the 21st Battalion, CEF (A rifle regiment carries its battle honours on its drums).

Instead, it provided one complete company to the Stormont, Dundas and Glengarry Highlanders (Glens), which went under canvas at the Kingston fairgrounds.

In June 1942, the 1st battalion PWOR was formed under Lieutenant-Colonel E Cockburn, and it served in Sherbrooke, Quebec, and Debert, Nova Scotia, where it was deployed for east coast defence.

All told, the regiment supplied 1500 men for active service including one brigadier, four colonels and eight lieutenant-colonels.

On the colours was emblazoned the badge of the Stormont, Dundas and Glengarry Highlanders, 1939–1945, commemorating the service of PWOR members in that regiment.

Today, the regiment is composed of men and women from all walks of life including students, policemen and farmers.

[7] The regiment did not fight in the Boer War in South Africa, but contributed volunteers for the various Canadian Contingents.

The 253rd (Queen's University) Highland Battalion, CEF, was authorized on 1 May 1916, began recruiting in mid-autumn of 1916, and embarked for Britain on 29 April 1917.

In May 1917, the officers of the 21st Battalion had a cross built to commemorate their comrades lost in the hard fighting for Vimy Ridge.

Private George Williams, a carpenter, salvaged wood from the battlefield to make the cross, ten feet high and three feet across, which was painted white and bore a metal plaque, "In Memory of the Officers, NCOs and Men; 21st Canadian Infantry Battalion Killed in Action April 9th 1917".

During services held by the regiment and Association every April, the name of every 21st Battalion soldier killed at Vimy is read aloud.

[22] Hockey Hall of Fame inductees Captain George Richardson and Scotty Davidson played on the senior team.