When Great Britain declared war, Canada was automatically at war because it was part of the British Empire. Through most of the first year of the war, however, Canada had to work just to muster, organize, and train a war ready army.
Assassination of Archduke Ferdinand: 28 June 1914
Outbreak of the First World War: 28 July 1914
Schlieffen Plan and Plan XVII: Aug 1914
Canadian Mobilization: Aug. 1914.
Formation of the Canadian Automobile Machine Gun Brigade No. 1: Sept. 1914
First Canadian Contingent Embarks for Europe: 12-16 Oct 1914