Many battles preceded and followed, but none would be so costly on both sides as Antietam. No more would citizen soldiers populate both armies. Rather, they would now be known as professional veterans. For the Confederacy, the brilliance of Robert E. Lee would be needed to keep the southern army alive. Opposing him, a series of union generals would be tried. Many would fail. In the end, George McClellan would be called upon, a second time, to save the Union. Will he succeed, or will Lee lead southern armies to victory?