McClellan at Antietam

[LibertyAndUnion]

Both 67th Tigers and Saphroneth make good points about the difficulty of moving and coordinating armies in general, and some of the specific issues with movements of the Army of the Potomac in Maryland. I have great respect for their ideas and perspective. I'm not McClellan hater. He made several good choices in early September and during the campaign. However, let's not forget the mindset of the man. A few weeks before Antietam, McClellan wrote the Union cause should be defeated for employing Pope. This was the view of the man in charge of the country's largest army. Winning a bloody war was outside of McClellan's skill set. Let's just face that reality.

One key point is that McClellan was still the ultimate one accountable. All generals are mere mortals who are going to make mistakes, not understand orders, not be in the right position at the right time, etc. If Burnside wasn't competent enough to command more than a regiment, per McClellan, why was Burnside given wing command in Maryland -- by McClellan? Burnside was far more successful in North Carolina than McClellan was anywhere, so I don't think his view of his old friend Burnside holds up. If Burnside was incompetent, keep him in command of the Ninth Corps in Washington's defenses in early September.

McClellan did view himself as on par with the greatest generals of history. He had the ultimate faith in himself. He simply didn't have greatness in him. As Grant suggested, the burden on McClellan, being picked as senior general in the U.S. Army before age 35, would be too much or nearly anyone, especially early in the war.

One key problem with McClellan after South Mountain: He acted (and wrote) as if the campaign was already won. His only true goal was kicking Lee out of Maryland. Carman, who walked and fought in the campaign -- and was therefore more informed about it than all of us combined -- strongly and logically argued as such. There was an insufficient sense of urgency in McClellan from the morning of 15th on. That likely explains why only two divisions were at the creek on the afternoon of the 15th, and why no troops moved west of the Antietam in mass until the afternoon of the 16th. Sure, other generals may not have been up to the task, but McClellan sure didn't seem too worried about moving with more alacrity. As a humorous Massachusetts man in the First Corps wrote of McClellan:

A prominent public man who knew McClellan as an engineer, before the war, once remarked that if he had a million of men it would take a million years for him voluntarily to move, which number is probably an exaggeration by several years.

I agree with 67th Tigers that launching a massive, well-coordinated attack on the 18th made far more sense. And for that, McClellan -- more than any other mortal -- deserves some criticism.

 

[LibertyAndUnion]

If Hooker moved and attacked on his own by late morning of the 16th, many of Jackson's men would not have been on the field. Lee had a skeleton crew on the morning of the 16th. But, again, the arguments against such an early move by one corps have merit.

 

[Saphroneth]

One key point is that McClellan was still the ultimate one accountable. All generals are mere mortals who are going to make mistakes, not understand orders, not be in the right position at the right time, etc. If Burnside wasn't competent enough to command more than a regiment, per McClellan, why was Burnside given wing command in Maryland -- by McClellan? Burnside was far more successful in North Carolina than McClellan was anywhere, so I don't think his view of his old friend Burnside holds up. If Burnside was incompetent, keep him in command of the Ninth Corps in Washington's defenses in early September.

When did McClellan come to that view about Burnside?

As for wing command, Burnside was one of the most senior generals so wing command is natural for him. You could swap 3rd and 9th Corps in terms of which goes to Washington, but I'm not sure of the specifics of how that decision was made so it could be that there were further negatives to it.

One key problem with McClellan after South Mountain: He acted (and wrote) as if the campaign was already won. His only true goal was kicking Lee out of Maryland. Carman, who walked and fought in the campaign -- and was therefore more informed about it than all of us combined -- strongly and logically argued as such. There was an insufficient sense of urgency in McClellan from the morning of 15th on. That likely explains why only two divisions were at the creek on the afternoon of the 15th, and why no troops moved west of the Antietam in mass until the afternoon of the 16th. Sure, other generals may not have been up to the task, but McClellan sure didn't seem too worried about moving with more alacrity. As a humorous Massachusetts man in the First Corps wrote of McClellan:

This is silly, though. In the first place, it's seven and a half miles from the South Mountain battlefield to the Middle Bridge (which is most of a day's march) and Sykes plus Richardson amount to about 12,000 men (i.e. a column about 3 miles long from the infantry alone) so that's about what you'd expect at ten miles a day; in the second place, the reason why it's Sykes and Richardson who reach the creek is that because 1st/9th Corps were being slow McClellan gave those two divisions right of way to push through (as they were fresher and thus faster-moving).
So McClellan prioritized speed in pursuing Lee's forces, it's just that because Lee retreated overnight he gained extra distance. At that, McClellan captured thousands of unwounded men, and one plausible place where that could have happened is Sykes and Richardson "running down" straggled Confederates on the road.

Remember that there's about 75,000 men (PFD) in the columns going through South Mountain. This many men, if they had no artillery or wagons, would form a column of fours about 18 miles long and take nearly two days to go past a single point; remember also that the Confederate troops at Harpers Ferry took multiple days to arrive at Sharpsburg, which is because of the same basic constraints on how fast units can move.

 

[Saphroneth]

If Hooker moved and attacked on his own by late morning of the 16th, many of Jackson's men would not have been on the field. Lee had a skeleton crew on the morning of the 16th. But, again, the arguments against such an early move by one corps have merit.

Not so skeleton as all that. By noon there were:

Longstreet's forces (48 regiments, counting DR Jones, Hood and Evans)
DH Hill's forces (23 regiments)
Ewell's forces (23 regiments) (which hadn't straggled as badly as Jackson's and got onto the field before noon on the 16th)
Plus Jackson and Walker, but if we ignore Jackson and Walker completely there's still 94 regiments on the field.


Hooker's 1st Corps has 42 regiments.


Now, of course there's straggling, but 1st Corps has straggling as well. They woke up at 3am on the 14th, advanced from Frederick to South Mountain (12 miles), fought at South Mountain, and then have moved another eight miles just to be in position for an attack before noon on the 16th; thus, in two and a half days they've moved 20 miles and fought a major battle.
(Compare to Ewell's corps, who in the same two and a half days have fought a battle and moved about 14 miles.)
1st Corps on the morning of the 17th had a strength on the field of about 9,000 effectives; on the morning of the 16th, with less chance to close up, it would be less.

 

[Saphroneth]

Sure, other generals may not have been up to the task, but McClellan sure didn't seem too worried about moving with more alacrity. As a humorous Massachusetts man in the First Corps wrote of McClellan:

A prominent public man who knew McClellan as an engineer, before the war, once remarked that if he had a million of men it would take a million years for him voluntarily to move, which number is probably an exaggeration by several years.

I agree with 67th Tigers that launching a massive, well-coordinated attack on the 18th made far more sense. And for that, McClellan -- more than any other mortal -- deserves some criticism.

I've quoted this bit because I think that it demonstrates the "McClellan can't win" rule.

What you have here, is that in the sections I've quoted you are criticizing McClellan for not moving fast enough and for attacking too soon.

As it happens, McClellan made a decision between speed and mass. He opted to go for a balance between the two.
I agree that it would have been better for him to emphasize "mass" more and "speed" less, given certain assumptions, but this has two issues to point out:
1) We don't know (and McClellan certainly didn't) whether Lee would still be there on the 18th if there was no threat on the 17th but a massive hammer was assembling to his north. Lee has an independent will and is quite capable of pulling back over the Shepherdstown fords overnight if he is about to take an attack he cannot endure.
2) If you're arguing that the better option would be to attack later then you can't really also blame McClellan for not attacking sooner. Friction happens, and while the commander should try his best to mitigate it there is only so much that can really be done in the real world - McClellan can't simultaneously stand over every wing commander and chivy them along, on top of the fact that much of his army is genuinely exhausted on the 15th. (9th Corps may not actually have slept much, if at all, on the night of the 13th/14th - they were in motion overnight.)

As it happens, on 3pm on the 13th of September McClellan's main body (1st, 2nd, 9th, 12th corps, plus Sykes and Morell) is entirely around or east of Frederick; less than four days later the whole of the 75,000-man main body is around Antietam Creek, and much of it is west of that creek. That's 22 miles and a major battle for a column of march in excess of 18 miles long, and for a ten-miles-per-day march you would expect it to take four days just to get the tail of the column there even without any fighting.
This may not be as urgent as people want, but straggling your army to bits by asking too much of it is exactly the mistake Lee commits in this very same campaign.

 

[LibertyAndUnion]

Yes, McClellan can't win. His philosophy of war prohibited him from winning. He was not the general to win the war. Reality proved that.

Jackson wasn't there until about noon on the 16th, and his forces were not concentrated when they arrived. It was the same type of problems McClellan faced. I don't disagree with many of your points. The logistical, coordination, and troop movement challenges he faced were exceedingly difficult. Lee faced the same problems with fewer men. They were hungry, tired, and lacked concentration, too. Jackson marched from Frederick to Harpers Ferry in 3 1/2 days. The First and Ninth Corps on the right wing of McClellan's army took twice as long to go nearly the same distance from either Upton's Hill or DC to the Monocacy. Carman said no reason existed why the AoP couldn't have been there by the evening of the 10th. His idea is far more compelling than McClellan's postwar myth making and whining.

The best thing given all the circumstances and the way the world played out by the afternoon of the 16th is what 67th Tiger suggested: A massive attack on the 18th. If McClellan couldn't get to the Antietam any faster -- something I very much doubt -- that's what should've happened. One corps across the creek in the afternoon of the 16th was far from the best reality. That's why I say he either should've moved faster or attacked later. I don't believe the idea is contradictory.

 

[67th Tigers]

It seems as though one of the basic problems at Antietam (including the movement from South Mountain, and indeed the fighting at South Mountain) was that McClellan could only be in one place at a time. And we notice the places where we might be able to point and say "McClellan could have helped here", but McClellan was also doing things in the places where he actually was so you end up with one of these things needed:

Hooker and Mansfield are the two officers who were recent McClellan picks to lead their corps, so it's plausible that there's some McClellan choice going on there which conceivably could have gone a different way. I'm not sure however who the alternatives would have been, as Mansfield was quite senior so the choice might well be him or leaving AS Williams in charge; Hooker was assigned in from 3rd Corps, and in fact was the only division commander of 3rd Corps who'd survived to that point, so again he's quite senior.

McClellan himself said as such in the West Virginia Campaign - that everything needed his personal attention as his subordinates were seriously lacking. It is almost a truism that the problem developed whereever McClellan wasn't, and that's likely because he was far more able than most of his subordinates.

McClellan wanted Slocum to take over the 12th Corps. He refused and preferred to remain in command of his division. This was unfortunate because Slocum turned out to be a far better commander than Mansfield.

Hooker was not picked by McClellan; he'd been promoted to corps command by Lincoln. Lincoln's orders a few days before Antietam were that the following were appointed to Corps command:

1st Corps - Reno vice McDowell
2nd Corps - Sumner
5th Corps - Hooker vice Porter
6th Corps - Franklin relieved, corps ordered to be attached to 3rd Corps
9th Corps - Burnside
12th Corps - Banks

McClellan protested these arrangements, and Lincoln allowed them to be suspended. However, he had raised Reno and Hooker to the "rank" of corps commanders. Reno didn't want to leave the 9th Corps. McClellan wanted to keep Porter, although I would not be so sure about Franklin. However, we know McClellan had come to consider Baldy Smith to be much worse than Franklin and so this may be the best of a bad job.

The only "choice" McClellan got was over who would command Banks' corps whilst Banks remained in Washington. He picked Slocum, but Slocum refused. During the battle the downing of Hooker allowed him to a pick commander out of turn to take the 1st Corps, and he chose Meade. He also had a very high opinion of Hancock, who he pulled to take over Richardson.

 

[Saphroneth]

Hooker was not picked by McClellan; he'd been promoted to corps command by Lincoln. Lincoln's orders a few days before Antietam were that the following were appointed to Corps command:

Ah, thanks for the correction.
It really looks like it's almost impossible for McClellan to get any different corps commanders except for losing the ones he actually had. It seems the options are:

1) For 1st Corps, it's either force Reno into 1st Corps command or keep him at 9th Corps.
2) For 5th Corps, it's either accept Hooker or keep Porter.
3) Banks at 12th, or Mansfield.

So you can have:

1st - Reno
5th - Hooker
9th - Burnside
or
1st - Hooker
5th - Porter
9th - Reno
or
1st - Reno
5th - Porter
9th - Burnside

I suppose there's an argument that the best choice would be Reno at 1st Corps (against his wishes), Porter at 5th, Burnside at 9th (also wing commander) and Hooker at 12th. But there simply aren't enough reliable commanders to have one everywhere you need one.

 

[Saphroneth]

The best thing given all the circumstances and the way the world played out by the afternoon of the 16th is what 67th Tiger suggested: A massive attack on the 18th. If McClellan couldn't get to the Antietam any faster -- something I very much doubt -- that's what should've happened. One corps across the creek in the afternoon of the 16th was far from the best reality. That's why I say he either should've moved faster or attacked later. I don't believe the idea is contradictory.

The simple reason to cross a corps in the afternoon of the 16th is to block the possibility of Lee moving north towards Pennsylvania. One corps isn't enough to attack on the afternoon of the 16th, but it is definitely enough to defend, and if McClellan can prevent Lee from escaping north then he's achieved a campaign goal (end the invasion); if McClellan doesn't prevent Lee from escaping north then he hasn't achieved that goal.

Now,I do happen to think that McClellan attacked too soon, but my understanding is that he thought the Confederate army was still divided. He has no way to tell McLaws and Anderson have arrived, not until Lee brings them out of reserve and deploys them to restore the situation when the attack is already under way, and so it's McClellan taking a calculated risk which failed; this sort of thing happens in war.

 

[Saphroneth]

The First and Ninth Corps on the right wing of McClellan's army took twice as long to go nearly the same distance from either Upton's Hill or DC to the Monocacy. Carman said no reason existed why the AoP couldn't have been there by the evening of the 10th. His idea is far more compelling than McClellan's postwar myth making and whining.

To be honest, I think there is a difference, actually two, and one of them is just that all the Confederate troops are veterans while huge chunks of the Army of the Potomac are brand new (untested and untrained).
But there's a second difference, and it's in the nature of the marches - which is that the Confederates are making a "route march" (that is, they are moving through terrain they know is largely clear of enemy forces) and the Union troops are making an "advance to contact" (that is, they are moving through terrain which may contain enemy forces, and in fact Lee only begins marching out of Frederick on the 10th with the Confederate rearguard leaving Frederick on the 11th). McClellan while moving has to do so in a way that his corps are in position for mutual support.


This is why 1st and 9th Corps hold position on the 10th, and then 2nd and 12th Corps hold position on the 11th - they're leapfrogging during a march to contact. McClellan has no way to reliably know that most or all of the Confederate army isn't still at Frederick until late on September 12th (which is when Stuart's screen is driven in past Frederick) and on the 12th all his corps are moving at once; on the 11th Frederick is still occupied by Confederate forces.

Certainly if McClellan's corps had gone full-bore in a single column down the Georgetown Pike they might have reached the Monocacy earlier (it's about 30 miles from Rockville to Frederick) but this would entail running into the Confederate cavalry screen by Urbana MD and AP Hill plus Ewell stationed along the Monocacy (which was their positions as of the 9th).
One of the worst situations for an attacking army to be in is making an attack down a single predictable axis and across a defensible terrain feature; the extra days of "wasted" time are needed for the Union army to advance on a broad front.

 

[Saphroneth]

Yes, McClellan can't win. His philosophy of war prohibited him from winning. He was not the general to win the war. Reality proved that.

It doesn't, though. What reality proves is that if you take a capable general and repeatedly break the promises upon which his planning was predicated, his plans can't produce a quick victory to the war.

You could argue that reality proves that you need at least 150,000 men PFD and ten months of concentrated strategic offensive to be able to take Richmond - but you can't argue that McClellan demonstrated himself able to do less than another commander given the same quantity of resources (absolute or relative).


As for McClellan's philosophy of war, McClellan's philosophy of war was quite modern. He wanted to combine "shock and awe" (i.e. a force so powerful that it is clearly pointless to attempt to fight it) with "hearts and minds" (i.e. reconciliation for anyone who does not actively support the rebellion, no atrocities or undue molestation of civilians) as a way to most strongly erode support for the Rebellion; he also wanted to exploit every single Union advantage at once (greater manpower, greater industrial might and access to overseas markets, sealane control, better artillery) to fight a campaign which the Confederates could not win.

Just look at what he does during the Maryland campaign in context.

At the end of August and the beginning of September, John Pope (a commander focused on hard-driving, advancing and aggression, commanding a large army which is being actively reinforced) has been routed by Lee's ability to suddenly concentrate troops against a vulnerable enemy who has until that point been on the attack. The rout sees many Union forces totally disintegrate, and it is in no small part McClellan's efforts which prevents the whole of Pope's army being harried to destruction.

A week later, McClellan leads an army out of Washington which is largely made up of the troops routed at Second Bull Run or otherwise from Pope's Army of Virginia (who make up elements of his 1st, 5th, 9th and 12th Corps), bulked out by green regiments along with two corps who hadn't been routed at Second Bull Run. This force has almost no training together and is still literally being put together on the move - 12th Corps is still "2nd (Banks) Corps, late Army of Virginia" when they march out of Washington - and nobody else wants the command, while Halleck keeps back an astonishing number of troops in Washington proper to defend it. (Over 80,000 men are left at Washington rather than marching out with McClellan's army, of which two divisions - Morell and Humphreys - are eventually sent.)

In the course of the campaign, McClellan ends Lee's invasion of Maryland. Perhaps he does not do so in the most efficient way, even given the army available, but we should realize that the only question people usually talk about is that McClellan failed because he did not destroy the entire Confederate army.

With the thrown-together fragments of two armies, one of them recently routed, and green troops, facing a recently-victorious force composed entirely of veterans and under the command of Lee.

If it were so easy to destroy Lee's army once McClellan's supposedly-malign influence were removed, it would have happened at some point in 1863 or 1864.

 

[67th Tigers]

Yes, McClellan can't win. His philosophy of war prohibited him from winning. He was not the general to win the war. Reality proved that.

Jackson wasn't there until about noon on the 16th, and his forces were not concentrated when they arrived. It was the same type of problems McClellan faced. I don't disagree with many of your points. The logistical, coordination, and troop movement challenges he faced were exceedingly difficult. Lee faced the same problems with fewer men. They were hungry, tired, and lacked concentration, too. Jackson marched from Frederick to Harpers Ferry in 3 1/2 days. The First and Ninth Corps on the right wing of McClellan's army took twice as long to go nearly the same distance from either Upton's Hill or DC to the Monocacy. Carman said no reason existed why the AoP couldn't have been there by the evening of the 10th. His idea is far more compelling than McClellan's postwar myth making and whining.

The best thing given all the circumstances and the way the world played out by the afternoon of the 16th is what 67th Tiger suggested: A massive attack on the 18th. If McClellan couldn't get to the Antietam any faster -- something I very much doubt -- that's what should've happened. One corps across the creek in the afternoon of the 16th was far from the best reality. That's why I say he either should've moved faster or attacked later. I don't believe the idea is contradictory.

Attack on the 16th

Jackson's division actually crossed at dawn on the 16th and rested for a few hours in the rear of Sharpsburg before being put into line about noon. They counted 1,500-1,600 who kept up with the march, which is the commonly used figure for Jackson. I suspect that the stragglers caught up after the division was counted and was closer to 4,000 than 1,500 (if the rate of catching up is the same as Ewell's and Walker's divisions, both of which were around 4,000 strong).

Ewell's division was actually ahead of Jackson's in the order of march but had halted at the ford the evening before which allowed the stragglers to close up a lot.

Walker's division had made a night march following Jackson's and arrived at the ford about dawn, but halted for several hours to allow their stragglers to catch up.

McLaws and RH Anderson of course would arrive until the evening of the 16th/ morning of the 17th. AP Hill would follow on.

If Hooker had moved alone in the morning, he'd have run into Jackson etc. as per OTL. The only difference is that Lee wouldn't have had McLaws and RH Anderson to hand as reserves.

An attack on the morning of 16th would have been much worse for the Federals than the attack of the 17th. In exchange for deducting RH Anderson and McLaws, the Federals lose 6th, 9th and 12th Corps and Morell's division.

Attack on the 18th

This could, of course, allow McClellan to get all his ducks in a row. It is far more the stereotype of McClellan, and obviously an untrue one.

The Federals would, of course, have their whole force available, but so would the rebels. They also had maybe ca. 10,000 stragglers that caught them up, plus AP Hill's whole division. Thus they were probably 15,000 effectives (+/- 2,000) stronger on the 18th than the 17th. They'd also have had a day to entrench if they wanted, and there is some evidence of Jackson's men starting entrenchment on the 16th.

In exchange oddly the Federals wouldn't have much else up on the morning of the 18th compared to the 17th (except 6th Corps of course is there). Couch is likely still in the Pleasant Valley because it isn't confirmed Anderson etc. aren't in the region, and Humphreys' division is still marching to the field.

If Lee stands, and McClellan puts 1st, 2nd, 6th and 12th Corps in in a single concerted attack (about 32,100 infantry effectives, of whom about 7,000 are raw recruits) on the northern flank, Lee can match them with an equal or greater force. Bizarrely, Lee has likely gained strength quicker than McClellan and if McClellan telegraphs in his intention to attack than Lee will be able to dig in to prepare for it.

 

[Saphroneth]

I'm not quite sure that 1st/2nd/12th corps wouldn't have gained at least some strength by waiting, but the point is fairly valid. In effectives on the field the Confederates had about 42,000 in the morning of the 17th; AP Hill gives another 5,000, and there's 10,000 ascribed as stragglers caught up in the analysis above.
Effectively this means that Confederate effective strength on the field has increased by about a third (if that 10,000 number is used); if it's only about 6,000 stragglers caught up, it still means an increase of a quarter.

The attacking force in the north on the 17th was 1st, 2nd and 12th, which in PFD (note not effectives) total a bit less than 44,000. 6th Corps adds another 12,000, to make it 56,000; in other words, the increase in strength is on the order of between a quarter (based on PFD) and a third (if 1st/2nd/12th corps can recover more stragglers themselves over the 17th).

Of course, the amount of strength Lee needs to fend off 9th Corps is fairly static.

This means that the attacking strength of McClellan and the defending strength of Lee in numbers have increased by about the same amount, to a first approximation. McClellan's attack has gained preparation and might strike as a single coordinated blow, but it's lost surprise; Lee has gained the chance to entrench, and any hope of gaining advantage from the exhaustion inflicted on Lee's army by South Mountain has evaporated (albeit there wasn't a great deal of hope for that historically, but an army's recovery is a process not an event).

There might be a gain from 9th Corps being ready to go, but 9th Corps should have been ready to go promptly in the historical battle; they'd had more than enough time.

What this means is that, basically, going on the 18th might be an improvement, but it's no panacea and might actually be a negative as well (though this is not quite as cut-and-dried as an attack on the 16th, which is obviously problematic).

 

[67th Tigers]

Tracking who fought in which phase (including those who fought in multiple phases):

	Federal			Confederate
Phase	Infantry	Guns	Cavalry	Infantry	Guns	Cavalry	Notes
Phase 1 - Miller Farm	12,261​	46​	500​	10,013​	73​	3000​
Phase 2- West Woods and Dunker Church	12,184​	58​	0​	7,834​	92​	0​	Includes Hancock and Irwin in Federal engaged
Phase 3 - Sunken Road	11,469​	6​	0​	7,497​	50​	0​	Includes Brooke in Federal engaged
Phase 4 - Middle Bridge	1,684​	20​	2,500​	2,900​	38​	0​	Residue of Garland and Colquitt estimated
Phase 5 - Burnside Bridge	9,370​	38​	500​	7,280​	38​	1,500​	Includes 2 bdes of AP Hill who were not engaged
Putative Phase 6 - Franklin's Charge	11,680​	36​	0​	10,651​	12​	0​	Attackers include 2 of Morell's Bdes, 4 of Franklin's and elements of 12th Corps. Rebel arty is that on the heights to the north, and does NOT include the massed artillery on the Hauser Ridge, behind the Dunker Church Ridge

 

[Saphroneth]

And if Franklin's charge fails, it's worth remembering that the Union army is vulnerable to almost complete destruction. It was only three weeks previously that Pope had attacked until his army couldn't resist a counterattack (whereupon he was routed from the field); this stuff was urgently recent for McClellan and everyone else involved.

 

[Saphroneth]

So I thought I'd try something interesting.

We know the size of McClellan's main body (going down the road from Frederick) was about 75,000 men PFD, or two and a half times the size of a classical Napoleonic corps.
We also know that the usual rule of thumb was that one corps could fit down one road in one day.
And we know that it's about 20 miles by foot from Frederick (which is a place where the main body has to use just one road) via the South Mountain gaps and Boonsboro to the Middle Bridge.

We know that 9th Corps began moving out of Frederick about noon on the 13th, and we know Morell's division (the rear of the column) arrived in the vicinity of the Middle Bridge before noon on the 17th.

So how long should it have taken?

Well, the usual rule of thumb for marching is ten miles per day.
The head of column starts moving at noon on the 13th, and it takes two and a half days for the whole force to go past; then another two days (10 miles per day) for the rear of column to reach the Middle Bridge. Which comes to four and a half days, so...
...the end of day on the 17th.

McClellan's main body moved overall faster than you'd expect on a route march, despite fighting a battle all day on the 14th.

 

[Cavalier]

I have never been able to make up my mind on what to think of McClellan. And now this discussion has given me a lot more to think about. Great stuff!

John

 

[Saphroneth]

I have never been able to make up my mind on what to think of McClellan. And now this discussion has given me a lot more to think about. Great stuff!

John

For my part, I don't think McClellan was amazing - I think he was more capable than he is usually considered, and the reason for this is that the challenges he faced are not sufficiently examined which means his achievements are not considered in the proper context.

What I suspect was the case for McClellan was that he had:

1) At least some natural command talent, and by that I mean that certain aspects of tactics and operations came easily to him relative to others.
2) Practical experience with logistics and rail lines.
3) Officer training.
4) Combat experience.

What he did not have was:

A) Good "political" skill, in terms of keeping his civilian superiors happy and properly following through the political ramifications - and propoganda potential - of his actions.
B) A period of seasoning in lower-level general officer roles. He goes up the ladder quickly and doesn't really have a period as an "executive general".

On top of that, he rose to command "early" (i.e. when expectations were still high and the hope existed that the war could be won both quickly and cheaply, and when the Union command structure was leavened with generals who hadn't had the worst shaken out - leading to problems with subordinates) and his political leanings (Democrat) made some high-up in government perpetually suspicious of him and even inclined to bring him down - whether or not he was the best commander for the job at the time.


This results in a picture of McClellan as a general who could employ the Union's advantages to bring an end to the war, given a certain amount of resources and freedom of action, and one who was better than the average run of Union generals - certainly better than the average Union general given the Army of the Potomac. He was not, however, a genius - just basically capable.

 

[LibertyAndUnion]

Thanks for all of your ponderings on these questions. As noted before, I respect the perspective of those who are more supportive of McClellan than I am, and you've raised several credible ideas here. Although I am critical of McClellan in several respects, I also wish to be fair and honest with the evidence. Perhaps Joseph Harsh said it best in his book about Lee and the Maryland Campaign: Before rendering judgment, a historian must be just. {or something like that}

 

[Saphroneth]

Thanks for all of your ponderings on these questions. As noted before, I respect the perspective of those who are more supportive of McClellan than I am, and you've raised several credible ideas here. Although I am critical of McClellan in several respects, I also wish to be fair and honest with the evidence. Perhaps Joseph Harsh said it best in his book about Lee and the Maryland Campaign: Before rendering judgment, a historian must be just. {or something like that}

I think one of the key questions for me when considering the actions of a commander is - what would have been a superior option?

In the case of the movement to Antietam for example, it's easy to say "it should have been quicker" but it's already quick - it's moving an entire army through a constrained road network.


We should also look at Lee's independent capability for action, because - and this deserves emphasizing - there are basically three options here.

1) McClellan performed as well as the "average" general in doing damage to Lee, and therefore "the average general" couldn't be reasonably expected to destroy Lee.
2) An "average" general would have been able to destroy Lee, and therefore McClellan was below average.
3) An "average" general would not have done as well as McClellan did, and therefore McClellan was above average.

Now, the important thing to consider about option (2) is that if it's true then Lee exposed himself to destruction. He didn't actually need to stand at Antietam - on any given evening Lee could have decided that he was too exposed to danger and pulled south of the Potomac. It only took a night for his whole army's fighting echelon to cross by the Shepherdstown fords, after all.
Indeed, the very fact that Lee not only remains at Sharpsburg but continues to pull in more reinforcements (ultimately the whole of the rest of his army) indicates that he felt there was an advantage to be gained by continuing to pull in more reinforcements and fighting it out at Sharpsburg... which means that either he thought that he could actually win the battle, or he thought that he could survive a day of attack by the Union army and then pull back.

Give that some serious thought. Even if Lee was only planning on standing until enough of McClellan's forces were through South Mountain to threaten him with destruction, it still means that Lee was probably hoping that McClellan would attack him prematurely.

This colours the whole of the conversation around Antietam itself, or rather it should. Because there's an implicit assumption of Lee at Sharpsburg on the 15th-18th as a "target" who will wait to be attacked, but Lee is a skilled general capable of operational manoeuvre and with good tactical sense. He will not simply wait there in a situation where any halfway competent general could squash him flat, but act to remove himself from that situation.

So as far as Lee was concerned he wasn't in that situation.