Officially it was not given a name and fell among the many nameless Canadian battalions raised to conform with the new numbering system introduced by Col. Sam Hughes, Canada's Minister of Militia and Defence in 1914.

[3] The battalion was raised as part of a response to the demand for fresh reinforcements early in 1915, as Canada struggled overseas with its single division.

[6] The Canadian Corps, including the 27th, would not participate in any major offensive for almost a full year, when the battalion would receive its "baptism of fire" at the Battle of St. Eloi, 5 kilometres from Ypres.

[citation needed] It was reported the officers of the 27th had not slept for over 100 hours, this was most apparent with the commander, Irvine R. Snider, a veteran of the North-West Rebellion of 1885 and the South African War, of the 27th Battalion who, during the Battle of St. Eloi, stayed awake for six straight days trying to relieve the strain "on his beloved boys".

When the Canadians arrived in the Somme Valley the British had been fighting for 3 months and they had traded 250,000 men for 8 kilometres of German trenches.

For example, at the Battle of Courcelette some of the men of the 27th brought green paint forward and marked the 250 prisoners they took with a rectangle and a circle above it as they sent back to the rear.

Lt. Robert Grierson Combe was posthumously awarded the Victoria Cross for his actions near Acheville, France on 3 May 1917.