You don't need violence to be effective.
(from that article)
It was not the violence that lead to change, but diplomacy... unless I'm missing something.
Regardless, it doesn't counter my point, unless you want to point out the revolutionary wars Australia and New Zealand had...
The unrests in Canada merely proved the point that the empire could not adequately control the colonies and they needed to become more self reliant.
This might sound generalist, but I don't think it's fair to look at America, Canada, Australia and New Zealand as separate reforms. They were all in the same empire that fell apart.
Anyway, I don't think there's ever diplomacy without at least _threat_ of violence.