Jacques, wtf? Where did you guys find the Carcass. I'm assuming it's British rather than French because the French weren't in the business of burning down towns when they were operating in lower and upper Canada...there weren't any that weren't French or friendly.
So; if British, taking your location into account, I'm thinking the siege of Quebec. I know Wolfe had Marines and Regulars encamped North East of Quebec City in preparation for the attack (Which occurred from the north embankment of the St. Lawrence river. South West of the walled City itself).
The French settlements in North America were not like the militaristic earthen 'forts' the British would build. These French settlements were towns, that had the ability to defend themselves but rarely had too...the usage of the carcass on these settlements would have been an effective (devastating) weapon against their citizenry and would make perfect sense to bring them.
Where pray tell, was it found? Just a general area, GPS isn't necessary. Just struck me. If nearer to Montreal, there was an old British (I'll maintain the carcass is British) Military Fort in Lachine. Either a civilian Blacksmith, or the forts armorer would have been making these in preparation for...?