Hull's supply lines ran for along the Detroit River and the shore of Lake Erie, which was dominated by the British armed vessels, making them vulnerable to British and Indian raiders. A raiding party under Tecumseh ambushed and routed an American detachment under Major van Horne on 4 August at the Battle of Brownstown, capturing more of Hull's despatches. Hull sent a larger party under James Miller to clear his lines of communication and escort a supply convoy of 300 head of cattle and 70 pack horses loaded with flour, which was waiting at Frenchtown, Michigan under Major Brush. Miller forced a British and Indian force under Major Adam Muir of the 41st Regiment to retreat some distance at the Battle of Maguaga on 9 August, but the British re-formed their line and he declined to resume the attack. Miller was ill and his losses in the engagement were heavier than those of the enemy, and he lost confidence and remained encamped near the battlefield until Hull ordered him to return to Detroit.