In 1939, Canada was the only independent nation in North America to declare war on Germany. A member of the British Commonwealth, Canada was nonetheless independent in foreign and defence policy and had been so since the Statute of Westminster in 1931. The British colonies in the Caribbean and in South America were not independent, and they went to war automatically as soon as Britain did on Sept. 3. But Canada waited until Sept. 10 to declare war. It should not have done so. Why? Because Canada’s national interests were not directly threatened by Germany. It was protected by the vast distances of the Atlantic Ocean from any attempts at major landings by German forces; no aircraft yet developed could attack Canada from Europe and there were no missiles that could do so. If such attacks ...