On Aug. 4, 1914, Britain entered into the conflict today known as the First World War. At that time, Canada did not conduct its own foreign policy and found itself also at war.
The next day, the Canadian government determined that it would raise a Canadian Expeditionary Force at its own cost, to serve in Europe alongside British and allied troops. For the Canadian military, this represented a problem because the tiny permanent army was not up to the task. Rather than mobilize the militia, it was decided to raise a separate force, using numbered battalions made up of active militia and civilian and veteran volunteers.