What if McLellan had continued the attack the day after Sharpsburg/Antietam?


Ad Honorem
Jul 2011
Could he have crushed the Confederates, forced Lee to surrender and have taken Richmond? Could he get his army to fight the next day? Would Lee have taken tactical counter measures or retreated or advanced his army somewhere?
Jun 2017
Yes, yes and yes. After taking advantage of those dropped orders to cut off Lee's invasion of the North, McClellan returned to being his incompetent, overly cautious self. McClellan vastly outnumbered Lee but left many of his troops in reserve and refused to reinforce Burnside. Lee also had his back to the Potomac and if McClellan had pursued Lee Grant style(as much as I think Grant's style of campaigning was horrible and incompetent) he could have attacked them as they were crossing the river. Lee was a great general and there's always the chance he could have pulled a rabbit out of his hat but I find it hard to believe that he would have been able to prevent his army from being destroyed if McClellan had done all he was capable of. To add insult to injury McCllelan then refused to follow Lee into Virginia claiming he didn't have enough men when he had almost a 3-1 numerical advantage.

After this Lincoln promoted the more aggressive Burnside, who probably would have ended the war at Sharpsburg had he been in command there but who was too aggressive in general and got over 10,000 troops killed in a dumb assault at Fredicksburg.

I'm curious how history would view McClellan if he'd won there and it's just weird to picture McClellan being seen in history as the hero of the Civil War. Seeing how McCllellan got the Democratic nomination in 1864 despite this embarrassment and that OTL's hero US Grant became President later on, there's a very good chance McClellan would have became a US President if this had come to pass. It's also weird to think about the Civil War ending in 1862 and how American history would be different without the almost 3 years of additional bloody fighting that killed hundreds of thousands of people.
Oct 2015
Not to mention that a victorious McClellan would probably have been elected president in 1864, and would NOT have proposed the XIIIth Amendment or defended emancipation against court challenges (if the proclamation was even issued after a decisive victory).
Last edited:
Apr 2012
The dispositions that morning were:

The above map is the positions (roughly) of the two armies at the end of the 17th. The only change Lee made on the night of the 18th was to pull back DH Hill's division and solidify his centre along the Hagerstown Road. Approximate effective infantry and cavalry strengths have been added using Carman's figures (with strengths filled in for units it is not reported) and an estimate of Federal straggling based upon observations of the First Army Corps. Confederate cavalry may be overestimated, but the 6,000 infantry stragglers who rejoined Lee on the night of the 17th-18th are not included.

McClellan shifted Morell to reinforce Burnside on the proviso this was a temporary reinforcement to support him if he were attacked. Burnside used the division to relieve his battleline, putting it west of the Antietam and thus stymieing any thoughts McClellan had about using them in the centre. Couch's division (maybe 5,000 effective infantry) arrived midmorning on the 18th, and was sent to Franklin, where two brigades formed left of Slocum, and another relieved Irwin's Brigade of Smith. Finally Humphreys arrived with his exhausted raw recruits (at most 5,000, and probably less) which McClellan used to try and wrestle Morell back from Burnside - and Burnside promptly put them into his reserve and didn't send Morell back!

McClellan's artillery has emptied their caissons, and any attack can't be supported with a large force of artillery. Artillery ammunition resupply arrived at Hagerstown late afternoon, and reached the army for the 19th.

With all this in mind, and with many of McClellan's Corps commanders objecting to renewing attack, especially Burnside and Sumner, what was McClellan supposed to do? The only option I can see, given his situation, is to launch an afternoon attack by Franklin on the Dunker Church again. If McClellan manages to get Morell back from Burnside (which might mean relieving Burnside of command) he might get 14,500 effective infantry from 5th, 6th and 12th Corps into action there. However that's essentially just a replay of the assault by 1st and 12th Corps and Sedgwick's Division (2nd Corps) assault of the late morning on the 17th, presumably with similar chances of success.

The options are:

1. Early morning. Send in Franklin's 5 unbroken brigades against the Dunker Plateau (the most heavily protected part of the enemy line) early on the 18th.

(6,500 assaulting 11,500)

2. Send the above plus Couch in late in the morning.

(maybe 11,000 assaulting 11,500)

3. Send the above (1 and 2) plus Morell in the afternoon (assuming getting Morell back from Burnside).

(maybe 15,000 assaulting 11,500)


Ad Honorem
Oct 2009
San Diego
Not to mention that a victorious McClellan would probably have been elected president in 1864, and would NOT have proposed the XIIIth Amendment or defended emancipation against court challenges (if the proclamation was even issued after a decisive victory).
Actually... If McClellan had won... he would have continued to be the head of the army and Lincoln would have gotten credit for the victory against the rebs.
Just as Lincoln got the blame for McClellan's failures, which was the entire basis of McClellans candidacy.

McClellan only went to politics because he was cashiered from the army.

So- an early win for the Union results in Lincoln having more time to work on reconstruction, a second term, and likely no assassination attempt.

That Gives the Republican party even greater incentive to forward their abolition agenda, once the peril is past... and the FACT of the war gives them ample justification to eliminate slavery as the proximate cause of the rebellion before the South can be reinstated in congress.

So- we get 6 more years of Lincoln... probably abolition passed. A much better reconstruction, and McClellan running for president after Lincoln's second term... with abolition a done deal.

And we get to avoid Andrew Johnson.