"The Battle of Quebec (French: Bataille de Québec) was fought on December 31, 1775, between American Continental Army forces and the British defenders of Quebec City early in the American Revolutionary War. The battle was the first major defeat of the war for the Americans, and it came with heavy losses. General Richard Montgomery was killed, Benedict Arnold was wounded, and Daniel Morgan and more than 400 men were taken prisoner. The city's garrison, a motley assortment of regular troops and militia led by Quebec's provincial governor, General Guy Carleton, suffered a small number of casualties."
They came to "liberate" the Canadian Colonies, but I guess it could have been to cut off their main focus from allies.
And whilst there was a small amount of Canadians who wanted to join the revolutionaries, a large majority either wanted to stay out of it, or sided with the British. Alot of American Loyalists ended up here after the war.