Shoulder title The Black Watch R.H.R. of Canada, 2nd Canadian Division

The 2nd Battalion was called out on service on 26 August 1939 and details of the battalion were placed on active service on 1 September 1939, as the 2nd Battalion, The Black Watch (Royal Highland Regiment) of Canada, CASF (Details), for local protection duties. These details were disbanded on 31 December 1940.

The regiment mobilized the 1st Battalion, The Black Watch (Royal Highland Regiment) of Canada, CASF, on 1 September 1939. This unit, which served in Newfoundland from 22 June to 11 August 1940, embarked for Great Britain on 25 August 1940. Three platoons took part on the raid on Dieppe on 19 August 1942. On 6 July 1944, the battalion landed in France as part of the 5th Infantry Brigade, 2nd Canadian Infantry Division, and it continued to fight in North West Europe until the end of the war. The overseas battalion was disbanded on 30 November 1945.

The regiment subsequently mobilized the 2nd Battalion, The Black Watch (Royal Highland Regiment) of Canada, CASF, on 18 March 1942. This unit served in Canada in a home defence role as part of Atlantic Command until it was disbanded on 15 August 1943.

The 1st Battalion, Black Watch was brigaded with Le Régiment de Maisonneuve and Les Fusiliers Mont-Royal of the Second Canadian Division, however the FMR were replaced with The Calgary Highlanders in the 5th Brigade in 1940.

The 1st Battalion suffered more casualties than any other Canadian infantry battalion in Northwest Europe according to figures published in The Long Left Flank by Jeffrey Williams. Disaster seemed to follow the unit;

• On the voyage to France on the day of the Dieppe Raid, casualties were suffered by the unit during a grenade priming accident onboard their ship, the HMS Duke of Wellington.
• During the Battle of Verrières Ridge on July 25, 1944, 325 men left the start line and only 15 made it back to friendly lines, the others being killed or wounded by well entrenched Waffen SS soldiers and tanks.
• On 13 October 1944 - known as Black Friday by the Black Watch - the regiment put in an assault near Hoogerheide during the Battle of the Scheldt in which all four company commanders were killed, and one company of 90 men was reduced to just four survivors.