that further defence was impossible and made preparations to destroy the blockhouse and schooner. A line of powder was set running to Nancy and from there to the blockhouse. At four o'clock, Nancy was set alight which in turn by way of the powder train, set off an explosion in the blockhouse. The blockhouse explosion surprised Sinclair, causing him to think that one of the howitzer's shots had found its mark. Worsley's party then retreated into the woods, having suffered one killed and one wounded. The Americans recovered the guns from the wrecked blockhouse and then felled trees across the river to block it. Sinclair departed for Detroit in Niagara, leaving the gunboats under Lieutenant Daniel Turner to maintain a blockade of the bay. Sinclair's orders were that the gunboats were to remain until they were driven from the Lake by bad weather in October, by which time it would be impossible for small boats to re-establish communications between the Nottawasaga and Mackinac. He did however authorize Tigress to cruise for a week or two around St. Joseph Island to intercept fur canoes. The gunboats' crews were reinforced by twenty-five men of the 17th U.S. Infantry, to serve as marines. Movements in late August The Americans had missed one hundred barrels of provisions in a storehouse, and two batteaux and Livingston's large canoe which had been moved higher up the Nottawasaga River toward the depot at Schoonertown. Worsley removed the obstructions from the river and sailed in open boats for Fort Mackinac with his sailors and Livingston, carrying seventy barrels, late on 18 August. Accounts of subsequent events vary; some state that Worsley evaded the gunboats, which were forced back into Lake Huron by a storm (which also nearly sank Niagara) a few days later, while others state that one or both gunboats had left the Nottawasaga almost as soon as Niagara was out of sight, hoping to capture boats and canoes involved in the fur trade with their valuable cargoes, and thus leaving the Nottawasaga unguarded. The Americans then heard that several boats manned by hired Canadian voyageurs under Captain J. M. Lamothe were attempting to reach Mackinac Island with supplies via the French River. To intercept this party, the gunboats cruised in a narrow channel about east of Mackinac Island, known as the Detour Passage. The voyageur party were warned and temporarily turned back up the French River.