You are bouncing between the Seven Years war, and the war of 1812.. but basically something called the Quebec Act in 1777 was the legal start of Quebec's "unique" status ---maintaining French.. all the way to today. But it was a hard fight. Quebec stayed Quebec a lot because of the catholic church as well.. just was such a predominant force.
I think in short the British victors figured it was easier to let Quebecers self rule, than to have them go all Revolutionary like in America (and France of course)
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View my fuel log 2014 Mirage ES 1.2 manual: 42.2 mpg (US) ... 17.9 km/L ... 5.6 L/100 km ... 50.7 mpg (Imp)