The last battle at Antietam took place on the Rebel right flank where the Union Army lead by General Burnside tried to fight its way across a strongly defended stone bridge over Antietam Creek. Burnside had 12,500 men and McClellan’s promise in supporting his attack. The Confederates held the bluff over looking the bridge and positioned sharpshooters there. As a result of the Rebel fire, it took three hours and three separate assaults before the Federals could get across the bridge. Burnside begged McClellan for the reinforcements he had promised; None came. Just as the Union began fighting its way toward Sharpsburg, A.P. Hill shows up to save Lee’s right and forces the Federals back to Antietam Creek and the bridge they fought so hard to seize. No ground had been gained by the Union and Lee’s right for the time being was safe.