Belgium’s ports were close to the British Coast and during the war Germany took control of Belgium. This was a major threat to Britain. On August 4th 1914 Germany attacked France through Belgium and within hours of the event Britain declared war on Germany.
During 1914 Canada and Britain were close allies. When the Britain joined WWI Sir Wilfrid Laurier proclaimed "It is our duty to let Great Britain know and to let the friends and foes of Great Britain