Technically distinct from the standing land forces of the Militia, soldiers were legally attested into the CEF in order to serve overseas. Hughes refused to mobilize the existing regiments as units, and instead numbered battalions were created into which a combination of Permanent Force regular soldiers, Militia reservists and civilian volunteers were combined.
The unit was assembled at Valcartier in Quebec, and sailed for the United Kingdom with the first Canadian contingent in late Their commanding officer was Lieutenant Colonel Russ L. Boyle, a veteran of the Boer War, and in the commander of the 15th Light Horse, an Alberta cavalry unit.
The unit trained on Salisbury Plain and went into the trenches in France in early with the rest of the Division. After brief service in the trenches in February and the early spring, the division first saw major combat at the Second Battle of Ypres in April. This the use of poison gas as a weapon of war on the Western Front.
A wide scale German attack using chlorine gas routed two entire French Divisions, but the 1st Canadian Division held firm, at a cost of some 6, of its 10, men. The town of St. Julien was located east of Ypres, in the south-western part of Belgium known as Flanders. The 10th Battalion was called forward on the night of April to counterattack the strong German formation advancing through a large gap in the line created by the rout of two French divisions.
Nonetheless, the German advance was stopped. This action moved the overall commander of the French Army to describe the attack as the single bravest act of the entire war. Also featuring prominently in the fighting was the Gravenstafel Ridge, a low rise east of Ypres and one of the key features in the German attacks from April. The 10th Battalion by this point, after suffering heavily in its counter-attacks of April, mustered only men but still contributed enough to the defence of the position to merit a Battle Honour for their work.
