Canadian soldiers in WWII were not terrorists.  WWII exemplified the notion of "total war".  It was not a war between armies, but between nations.  The entire nation was enlisted into the war effort through a nation's industrial capacity, among other activities.  By that definition, anything that could degrade a country's industrial output was fair game.  Participating in such a war does not make one a terrorist.

terrorism |ˈtɛrəˌrɪzəm|
noun
the unlawful use of violence and intimidation, especially against civilians, in the pursuit of political aims