They then attacked the British post at St. Joseph Island on 20 July but found that it had been abandoned. On 4 August, they attacked the main British position at Fort Mackinac but were repulsed with heavy losses at the Battle of Mackinac Island. Action at Nottawasaga In spite of their victory, the British at Mackinac were very short of provisions and would starve if they were not resupplied before Lake Huron froze at the start of winter. Sinclair had earlier captured a small schooner (Mink) belonging to the Canadian North West Company, and learned from one of the prisoners that the British supply base was at Nottawasaga Bay. Having sent Lawrence and Caledonia back to Detroit with the militia, he arrived at the Nottawasaga with Niagara, Scorpion and Tigress on 13 August. The British detachment at Nottawasaga consisted of a midshipman and 21 sailors of the Royal Navy under Lieutenant Miller Worsley, and 9 French Canadian voyageurs. The schooner HMS Nancy was present at the Nottawasaga, loaded with 300 barrels of provisions (salted pork, flour, spirits etc.) for the garrison at Mackinac. A few days before the Americans appeared, Lieutenant Robert Livingston of the Indian Department had arrived, carrying a warning from Lieutenant Colonel Robert McDouall, the commandant at Mackinac, of the American presence. Nancy was towed up the Nottawasaga River, and a crude blockhouse armed with two 24-pounder carronades removed from Nancy and a 6-pounder field gun was hastily constructed for her protection. Livingston had proceeded onwards to York to request reinforcements, but none were available. (Almost all the British regular troops in Upper Canada were already engaged in the Siege of Fort Erie, and the militia could not be persuaded to turn out.) On his return, Livingston was able to gather 23 Ojibwa to help Worsley's party. The Americans believed that Nancy was still en route to the Nottawasaga and intended to intercept the schooner on the lake, but on 14 August some of Croghan's troops landed to set up an encampment on the spit of land at the mouth of the river and foraging parties chanced on the schooner's hiding place. The next day, Croghan's troops (three companies of regular infantry) landed and attacked. The American vessels opened fire over intervening sand hills without success, but the Americans then landed a detachment of artillery with one (or two) 5.5-inch howitzers to support the infantry. Worsley decided