An already tense situation in the Balkans was exacerbated when, on June 28, 1914, a young Serbian nationalist assassinated Archduke Ferdinand of Austria-Hungary. Hostilities began slowly but over the summer months friends and allies lined up on one or the other side of the conflict. Once Austria declared war, Russia supported Serbia and Germany went to the aid of Austria. France soon aligned with Russia and, when Germany attacked France via Belgium, Britain entered the fray. Britain at war meant the colonial members of the Empire were at war and so Canada took up arms.

War World II was spawned by a major economic depression, a single man's - Adolph Hitler's - mesmeric will to do evil, and a rather sluggish response by his subsequent opponents. The aggressive policies of the Axis powers (Germany, Italy, and Japan) culminated in the seizure of Bohemia and Moravia in March 1939. When Hitler attacked Poland on September 1, 1939, England and France declared war. This time, Britain at war meant that most members of the Commonwealth were at war and so once again Canada took up arms.