Washington was now too strongly held to be attacked, but Lee determined to invade Maryland.  At least this would keep Virginia safe during harvest time.  It might win him many recruits in Maryland.  It would frighten the North, all the more because a Confederate force further west was at that same time invading Kentucky; it might accomplish there was no saying how much.  This much, one may gather from the “Life of Lord John Russell,” any great victory of the South on Northern soil would probably have accomplished:  the Confederacy would have been recognised, as Jefferson Davis longed for it to be, by European Powers.  Lincoln now acted in total disregard of his Cabinet and of all Washington, and in equal disregard of any false notions of dignity.  By word of mouth he directed McClellan to take command of all the troops at Washington.  His opinion of McClellan had not altered, but, as he said to his private secretaries, if McClellan could not fight himself, he excelled in making others ready to fight.  No other step could have succeeded so quickly in restoring order and confidence to the Army.  Few or no instructions were given to McClellan.  He was simply allowed the freest possible hand, and was watched with keen solicitude as to how he would rise to his opportunity.

Lee, in his advance, expected his opponent to be slow.  He actually again divided his small army, leaving Jackson with a part of it behind for a while to capture, as he did, the Northern fort at Harper’s Ferry.  A Northern private picked up a packet of cigars dropped by some Southern officer with a piece of paper round it.  The paper was a copy of an order of Lee’s which revealed to McClellan the opportunity now given him of crushing Lee in detail.  But he did not rouse himself.  He was somewhat hampered by lack of cavalry, and his greatest quality in the field was his care not to give chances to the enemy.  His want of energy allowed Lee time to discover what, had happened and fall back a little towards Harper’s Ferry.  Yet Lee dared, without having yet reunited his forces, to stop at a point where McClellan must be tempted to give him battle, and where, if he could only stand against McClellan, Jackson would be in a position to deliver a deadly counter-stroke.  Lee knew that for the South the chance of rapid success was worth any risk.  McClellan, however, moved so slowly that Jackson was able to join Lee before the battle.  The Northern army came up with them near the north bank of the Potomac on the Antietam Creek, a small tributary of that river, about sixty miles north-east of Washington.  There, on September 17, 1862, McClellan ordered an attack, to which he did not attempt to give his personal direction.  His corps commanders led assaults on Lee’s position at different times and in so disconnected a manner that each was repulsed singly.  But on the following morning Lee found himself in a situation which determined him to retreat.