Were what the Germans called the Canadian army Shock Troopers. No one is 100% sure why the Germans called these Canadians Stormtroopers. However it is believed because the Canadian troops were known for Hitting Hard and Precise.
This is also supported by the fact that the Canadian troopers found a way through the German Gasses ("Kept pushing on").
The Germans later used the name "Stormtrooper" for their own Elite soldiers in WW2.
In WW1 the Canadians were known as "Stormtroopers of the British Empire".