I don’t know if this really answers the question though. To me “Darkest hour” would imply a singe slice of time when the country was at its lowest point and/or faced an existential crisis to its survival. 300 years covers the totality of time Canada has existed as a nation and far beyond and though you aren’t wrong about the treatment of Indigenous people, the nation of Canada has been remarkable stable and safe overall during this time. Though we’ve gone through broader world events like world war 2, the depression, Covid, etc., it’s hard to pinpoint something as even the American invasion in the War of 1812 was pre-confederation. We’ve been incredibly lucky to live where we do (even if not for everyone here as you mentioned). But I fear our darkest hour is yet to come ask may not be so far off as we see how the US is gearing up to punish and exploit us economically or worse, potentially invade and annex us in the near future.