The first formation so designated was a fully manned and equipped combat division which operated as part of the Canadian Expeditionary Force. The Division distinguished itself in several hard fought campaigns, and was disbanded at the end of the First World War. A second iteration was raised for the Second World War, and served in II Canadian Corps. A duplicate division was raised for duty with the Canadian Army Occupation Force in 1945. This article deals with the First World War formation which served in the Canadian Corps.

The Division was formed in France in Dec 1915, and served in France and Flanders until the Armistice. The Division originally fought under the command of Major-General M.S. Mercer, who became the highest ranking Canadian officer killed in action in the First World War. Brigadier V. A. Williams, commanding the 8th Brigade, became the highest ranking Canadian officer captured in the First World War, also at Ypres. Mercer was replaced by Louis Lipsett, who was also killed in action.

Order of Battle

7th Canadian Brigade
	Royal Canadian Regiment	Dec 1915 - 11 Nov 1918
	Princess Patricia's Canadian Light Infantry	24 Dec 1915 - 11 Nov 1918
	42nd (Royal Highlanders) Battalion	Dec 1915 - 11 Nov 1918
	49th (Edmonton) Battalion	Dec 1915 - 11 Nov 1918
8th Canadian Brigade
	1st Bn Canadian Mounted Rifles	Dec 1915 - 11 Nov 1918
	2nd Bn Canadian Mounted Rifles	Dec 1915 - 11 Nov 1918
	4th Bn Canadian Mounted Rifles	Dec 1915 - 11 Nov 1918
	5th Bn Canadian Mounted Rifles	Dec 1915 - 11 Nov 1918
9th Canadian Brigade (Joined the Division in Jan 1916)
	43rd (Cameron Highlanders) Battalion	Jan 1916 - 11 Nov 1918
	52nd (North Ontario) Battalion	Jan 1916 - 11 Nov 1918
	58th (Central Ontario) Battalion	Jan 1916 - 11 Nov 1918
	60th (Victoria Rifles) Battalion. Disbanded.	Jan 1916 - 30 Apr 1917
	116th (Ontario County Infantry) Battalion	Apr 1917 - 11 Nov 1918

9th Brigade Canadian Field Artillery

31st Field Battery
33rd Field Battery
45th Field Battery
36th Howitzer Battery

10th Brigade Canadian Field Artillery

38th Field Battery
39th Field Battery
40th Field Battery
35th Howitzer Battery

Divisional Units

3rd Division Ammunition Column
3rd Brigade Canadian Engineers
- 7th, 8th and 9th Battalions
3rd Divisional Signal Company
3rd Canadian Pioneer Battalion. 8 Jan 1916 - May 1917 (Disbanded)
123rd Canadian Pioneer Battalion. Mar 1917 - Jun 1918 (Moved to 3rd Canadian Engineer Brigade.)

Canadian Machine Gun Corps

7th Machine Gun Company

8th Machine Gun Company

9th Machine Gun Company

15th Machine Gun Company

In early 1918, infantry machine gun companies were consolidated into Machine Gun Battalions, one per division. At first the battalion had three companies, and in May 1918 this increased to four, with a total complement of 96 Vickers Guns. The 3rd Canadian Machine Gun Battalion was formed for the 3rd Division.

Militia Regiment Parentage

The following is a list of the Militia Regiments in Canada that provided soldiers for the numbered infantry battalions.

7th Canadian Brigade	Royal Canadian Regiment	Prewar Regular unit
	Princess Patricia's Canadian Light Infantry	Privately raised
	42nd (Royal Highlanders) Battalion	5th Regiment (Royal Highlanders of Canada)
	49th (Edmonton) Battalion	101st Regiment (Edmonton Fusiliers)
8th Canadian Brigade	1st Bn Canadian Mounted Rifles	22nd Saskatchewan Horse 21st Alberta Hussars
	2nd Bn Canadian Mounted Rifles	30th Regiment (British Columbia Horse) 21st Alberta Hussars
	4th Bn Canadian Mounted Rifles	Governor General's Body Guard 9th Mississauga Horse
	5th Bn Canadian Mounted Rifles	7th Hussars XI Hussars 27th Light Horse
9th Canadian Brigade	43rd (Cameron Highlanders) Battalion	79th Cameron Highlanders of Canada
	52nd (North Ontario) Battalion	96th The Lake Superior Regiment
	58th (Central Ontario) Battalion	10th Regiment (Royal Grenadiers)
	60th (Victoria Rifles) Battalion. Disbanded.	3rd Regiment (Victoria Rifles of Canada)
	116th (Ontario County Infantry) Battalion	34th Ontario Regiment

Battles and Engagements

France and Flanders
Battle of Mount Sorrel. 2-13 Jun 1916.
Battle of Flers - Courcelette. 15-22 Sep 1916.
Battle of Thiepval. 26-28 Sep 1916.
Battle of Le Transloy. 1-18 Oct 1916.
Ancre Heights 1 -11 Oct 1916.
Vimy 9-14 Apr 1917.
Attack on La Coulotte. 23 Apr 1917.
Third Battle of the Scarpe. 3-4 May 1917.
Affairs South of the Souchez River. 3-25 Jun 1917.
Capture of Avion. 26-29 Jun 1917.
Hill 70 15-25 Aug 1917.
Passchendaele 26 Oct-10 Nov 1917.
Amiens 8-11 Aug 1918.
Actions around Damery. 15-17 Aug 1918.
Battle of the Scarpe. 26-30 Aug 1918, including the capture of Monchy le Preux.
Canal Du Nord 27 Sep-1 Oct 1918, including the capture of Bourlon Wood.
Battle of Cambrai. 8-9 Oct 1918, including the Capture of Cambrai.
Valenciennes 1-2 Nov 1918.
Pursuit to Mons 11 Nov 1918.

Commanders

Major General M.S. Mercer, CB (24 Dec 1915 - 2 Jun 1916)
Major General L.J. Lipsett, CB, CMG (16 Jun 1916 - 12 Sep 1918)
Major General F.O.W. Loomis, CB, CMG, DSO (13 Sep 1918 - 11 Apr 1919)

Insignia

Beginning in mid-1916, the Division adopted a system of coloured Battle Patches which were worn on both sleeves of the Service Dress jacket as well as the greatcoat. A rectangle 2 inches tall by 3 inches wide in black was adopted to distinguish the 3rd Division from other formations of the Canadian Corps. In short order the colour was changed to French Grey. Coloured geometric shapes used in combination with the divisional patch distinguished individual formations, units and sub-units within the division. The markings were also seen painted on steel helmets, vehicles and used as road signs. The diagram below is a representative list only.