That day ended with an evening rally of more than a thousand people, protesting the Governor General’s signing of a bill.

That morning, as usual, Lord Elgin left his official residence to head to Parliament. In the Legislative Council chamber, he granted Royal Assent—the news spread quickly—to the bills passed during the session. Among them was one law denounced by Tory opponents: the Act to indemnify persons in Lower Canada whose property had been destroyed during the 1837 and 1838 rebellion. Once the ritual was over, at day’s end, the Governor left Parliament to return home to Monklands. But, he would later recount, “a small group of people” was waiting for him as he left Parliament. The moment he took his seat in his carriage, a shower of improvised projectiles rained down on him.

8 p.m., at the Champ-de-Mars. That was the meeting time set by the Montreal Gazette to rally disgruntled Tories over the Rebellion Losses Bill being approved by Governor Elgin, at the request of Louis-Hippolyte LaFontaine’s Reform government. Nearly 1,500 people answered the call, and several delivered fiery speeches, including Alfred Perry, head of a volunteer firefighters’ brigade. But the English-language press instead accused LaFontaine of inflaming the debate by introducing the bill to compensate the victims of the rebellions—as this cartoon published in Punch in Canada suggests.

Perry is now widely recognized as one of the main instigators of the fire—and he admits as much in his own account of the event, published in 1887. At the Champ-de-Mars, before a crowd of angry men, he declared: “The time for petitions is over. If the men here are serious, let them follow me to Parliament.”

The end of Montréal as a capital was not far off.