How did the Confederate win the Battle of Antietam?

Answer 1

In point of fact, the Seven Days Battles were a Union victory in most respects. McClellan, the Union commander, inflicted twice as many casualties on Lee's army than Lee inflicted on his. Also, McClellan did not lose the battle at Malvern Hill. On the contrary, McClellan smashed the Confederates at Malvern Hill, and Lee later said he regretted ever attacking the hill because he lost so many men trying to take it. And McClellan's retreat to Harrison's Landing was a tactical retreat that forced Lee to go back to Richmond and left McClellan in a position to still threaten Richmond.

It's worth mentioning that Lee never would have been able to start the Seven Days Battles if Lincoln and Stanton had not made the awful mistake of withholding McDowell corps of 30,000 troops from McClellan's force. Lee would have been pinned to Richmond if Lincoln had followed through on his promise to send McDowell's corps to McClellan.

My sources include Ethan Rafuse's book McClellan's War, Thomas Rowland's book George B. McClellan and Civil War History, and H. J. Eckenrode and Bryan Conrad's book George B. McClellan: The Man Who Saved the Union.

Answer 2

With Robert E. Lee now in charge of the Southern armies defending Richmond during the Peninsula campaign, there are several factors to consider regarding the Confederate victory. For two straight days, lee has sent assaults against McClellan's forces at MechanicsVille and at Gaine's Mill. The assaults are not perfect pictures, however, the Union cannot make an advance on Richmond while holding off Lee's offensive. Despite the fact that president Lincoln will not send reinforcements, and that Lee's attacks are poorly coordinated, the Union falls back. Lee does break the Federal lines on the 27th however, the Union's V Corps escapes defeat by retreating south. The end result of that is that Lee has cut McClellan's supply lines. McClellan makes the decision to retreat through the swamps and reorganize along the banks of the James River.