 At the Battle of Antietam (September 17, 1862), the Second was again called to assault a well-entrenched Confederate force.Union commander George B. McClellan had tasked Burnside with opening up a southern front to the battle to divert Confederate forces from a simultaneous attack taking place on the north end of the field.Burnside attempted to throw his corps across Rohrbach's bridge, a small stone crossing henceforth known as "Burnside's Bridge."