ON JULY 2, 1812, the schooner Cuyahoga, a private American vessel, sailed from Lake Erie into the mouth of the Detroit River and past Fort Amherstburg, a British stronghold on the Canadian side of the river. Unknown to those on board, the United States had formally declared war against Great Britain. But the British at Amherstburg knew. They seized the ship from the surprised crew and were rewarded with papers belonging to American brigadier general William Hull. Among them: correspondence outlining an invasion of Canada.