During the Peninsula Campaign of 1862, Confederate president Jefferson Davis had appointed a new commanding officer, General Robert E. Lee. A brilliant and audacious tactician, Lee was a graduate of the U.S. Military Academy at West Point. He was also a native of Virginia, however, and although he was reluctant to fight against his government, he believed it was his duty to fight for the Confederacy. Upon his appointment by Davis, Lee was determined to pursue the Union army into the North, where he believed a successful campaign against Washington, D.C., would persuade the Union side to ask for peace terms. Lee crossed the Potomac into Maryland on September 7, 1862. Ten days later, he fought McClellan's army to a bloody stalemate at the Battle of Antietam. Having lost a quarter of his men, fearing a counterattack, and seeing his supply lines threatened by Union cavalry, Lee...