What wars or missions have have Canadian troops helped?
Monte Cassino, Italy
Attack on Gothic Line, Italy
D-Day invasion of Normandy, France (one of the 5 beaches were dedicated to the Canadians)
There were not a lot of wars that Canada fought in by themselves. They were a part of Great Britian, so they fought with them in many wars prior to WW2, including WW1.
The Underground Resistance and general populous helped to sabotage the Germans and Japanese. This greatly helped the troops. They also gained intelligence from the people of the nations they fought in. This really helped them, particularly when an enemy soldier would spill the beans. This was true for both wars. See links below.