"Ah! les Canadiens! C'est possible!."
When the USA joined the allied powers in the Great War on 6th April 1917, Britain and her Empire had already been engaged in bloody conflict for three long years. But that's not to say that our North American Continental cousins hadn't already been deeply committed.
On Easter Monday, 9th April 1917, a Canadian Corps that contained elements from all nine provinces did the impossible and captured Vimy Ridge. In 1915 a French attempt to take the ridge cost them 150,000 casualties. They considered its capture impossible. The ridge remained in allied hands throughout the war and was pivotal in breaking the German offensive of 1918.
Thank you, Canada.