 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.After the action, the gunboats "Scorpion" and "Tigress" were left to guard the river to prevent canoes and bateaux from getting supplies to Fort Mackinac.