Brock originally intended to occupy a fortified position astride Hull's supply line and wait for starvation and bombardment to force the Americans to surrender or come out to fight, but he then learned that Hull had sent a detachment of 400 men the previous day under Colonels Cass and McArthur to escort Brush's convoy to Detroit via a backwoods trail some distance from the lake and river, and this detachment was only a few miles from the British rear. (Hull had sent messengers recalling this force the night before, but Cass and MacArthur had already encamped for the night and declined to move.) To avoid being caught between two fires, Brock advanced immediately against the rear of Fort Detroit, the side farthest from the river where the defences were weakest. Tecumseh's warriors, meanwhile, paraded several times past a gap in the forest where the Americans could see them, while making loud war cries. Militia cavalry leader William Hamilton Merritt noted that "Tecumseh extended his men, and marched them three times through an opening in the woods at the rear of the fort in full view of the garrison, which induced them to believe there were at least two or three thousand Indians." Merritt was not an eyewitness, however, and this claim has been disputed.