Who the Hell knows - It's like that mid summer holiday - don't celebrate Simcoe day in August either - to me it's just a civic holiday - I'm french!
In our traditions (and apparently, not a lot a my french coworkers/teachers know this) we celebrate Dollars des Ormeaux in french ontario.
Here's a quote from a history blurb of French Canadian history:
"Le 21 mai 1660 passe dans l'histoire comme le jour où Dollard des Ormeaux sauva la Nouvelle-France."
Against the attack by hundreds of Iroquois, Dollard and his handful of volunteers fought to the death.
"The Iroquois returned to their villages disturbed by the fact that they had lost more than eighty warriors against such a small number of defenders. The fear of suffering significant loss in an attack by the men of New-France discourages the Iroquois from attacking again." (loose translation)
However, I guess I haven't answered your question - There has never been a Victor quite as important in our (english) history, as Queen Victoria, and so she remains the subject of most Canadian's reason for a holiday next Monday.