When has that ever happened? In fact the Canadians have always done a good job of kicking the crap out of other bullies during WW1 &WW2, years before we even showed up. Canadians can take care of themselves if they have to. In fact it wasn't until ww2 that the size of our military became bigger than theirs. Despite the years afterwards of liberal neglect and downsizing of Canada's military, what's left are still top notch soldiers, airmen and navy.
I was speaking more in general terms. While the United States has never had to rescue Canada, per se, it’s come to the rescue of other countries that Canada couldn’t rescue on it’s own but wanted rescued.