One hundred years after the beginning of the First World War, Canada's involvement in that conflict is seen as a formative event in this country's history.

Unlike our southern neighbours, Canadians showed little ambivalence about getting involved.

The conflict effectively began on Aug. 4. Britain had given Germany a deadline to respect Belgium's neutrality. When that deadline passed without a concession from Germany, Britain declared war.

Robert Borden, Canada's prime minister at the time, said, "We stand shoulder to shoulder with Britain, and the other British dominions, in this quarrel."

And so the call for volunteers went out in Canada, and 40,000 Canadian men assembled.

The speed and eagerness of Canada's response is captured in Lest We Forget, a 1935 documentary produced by the Canadian government's Motion Picture Bureau.

Canada in the First World War

Canada entered the First World War in 1914 mere weeks after Britain declared war on Germany. (CBC)

"From every part of Canada, from every walk of life, came swift response," says the documentary's narrator. "From the offices and workshops of the great cities, from the surf-beaten shores of the Maritimes, from the banks of the majestic St. Lawrence and its hundred affluents in the central provinces, from the shores of the Great Lakes, from the wheatfields of the west, from the fruitful slopes and broad acres of the Pacific coast, Canadians rallied to the cause."

Six weeks after the declaration of war, 33,000 Canadian men headed across the Atlantic in an armada bound for war. On Oct. 3, 1914, the ships carried the largest contingent of soldiers the government of that time had ever assembled.

Over the course of the war, approximately 619,000 Canadians enlisted in the expeditionary force for service overseas.

Canada's decisive role in pivotal battles such as Vimy Ridge and Passchendaele helped the country gain international standing, but it came with a cost: over the duration of the war, 61,000 Canadian soldiers lost their lives.