As ever, McClellan believed the Confederates to be stronger than was really the case. And he took too long to send in General Joseph Mansfield with the second corps. Once they were across the bridge, however, Mansfield’s men made a terrific effort and came within a few minutes, or a few hundred yards, of piercing the Confederate defensive lines in two. But as so often happened on that day, Lee brought some men from his right flank, which had not yet been assaulted, and managed to hold the Union men off. By this time, General Mansfield was mortally wounded, and General Joseph Hooker was out of combat, having suffered a bullet wound to his foot.
General Ambrose Burnside faltered during the Battle of Antietam, failing to take an important bridge quickly enough and then holding back instead of attacking vulnerable Confederate forces.