McClellan What Would McClellan Have Done?

[DanSBHawk]

But Magruder says that it's to happen under any circumstances. And he says if we are forced to retire.

So if McClellan breaks through, that is a circumstance under which Magruder's army is forced to retire. And that circumstance is one in which Magruder adds two regiments to the Yorktown garrison.


Now.

What benefit does it give Magruder to then pull out of the Yorktown garrison? Because it benefits McClellan quite significantly for Magruder to pull out of the Yorktown garrison, because it gives McClellan almost a month and lets him set up his forward positions and supply base around Eltham's Landing within about two days of Yorktown being abandoned. From Yorktown being abandoned to McClellan reaching Bottom's Bridge, with the historical weather, is a bit less than two weeks.

Would Magruder rather McClellan reach Bottom's Bridge on May 17 (historical date) or April 20 (two weeks after a breakthrough on April 6)?

I guess it all depends whether Lee was willing to throw away 3000 soldiers that he could have later used in battle against McClellan near Richmond, and... it also depends on how long McClellan is going to let 3000 confederates delay his offensive.

 

[Saphroneth]

I guess it all depends whether Lee was willing to throw away 3000 soldiers that he could have later used in battle against McClellan near Richmond, and... it also depends on how long McClellan is going to let 3000 confederates delay his offensive.

Well, it's not automatically "throwing away". It's only throwing away if they cannot be evacuated, and that requires the Union to be able to interdict the York even at night (to prevent the Confederates from evacuating in steamers at night).

But let's say McClellan does this in as efficient a manner as possible - that is, he is an "ideal" general, within the bounds of what you think is possible, against a reasonably capable enemy. He breaks through at the Redoubts on April 6 and encircles Yorktown, but Magruder withdraws north up the Peninsula with most of his force and garrisons about 3,000 men in Yorktown.


How soon can McClellan gain control of Yorktown, in your view, and how does he do it? You've indicated that you think besieging it would make McClellan look silly, so is that genuinely his only option, or is there some other way to do it?

 

[67th Tigers]

Even if they can't be evacuated, they are not "thrown away," but rather they've been spent. For a brigade, Magruder gains about a month, allowing a massive concentration before Richmond.

 

[Saphroneth]

Quite - this is exactly the kind of calculation made as part of military science. It's why fortifications on vital communcation routes existed.

I've already mentioned Badajoz, but another example is San Sebastian. This fortified position was garrisoned by about 3,000 troops and delayed Wellington's offensive into France by two months; the troops were all lost, but it brought time for the French to significantly reinforce their positions - from entering France in late June in a state of complete disruption, the French were able to reinforce themselves by about a third and launch on a fresh offensive by the end of July, at which point San Sebastian hadn't even fallen yet.


This is literally what forts are for. They either earn you time, or in assaulting them without prep work the enemy loses heavily.


The thing is, if McClellan does attack the Warwick line, and break through (rather than simply incurring heavy casualties, which could certainly happen when a strong defensive position was assaulted - see, say, Fredericksburg) then there's the possibility for the Union to, by these means, speed up the campaign... but only if the Confederates let them.

This is because the Confederates can, by holding Yorktown until it is reduced, delay the campaign until it's on more-or-less the historical timescale again. That's a Confederate choice.

If you think it's a benefit to McClellan to speed things up, then obviously it's a detriment to McClellan for things to not be sped up. And it's generally considered to be a good rule in war that the enemy is trying to cause you problems.

 

[JackADriscoll]

Quite - this is exactly the kind of calculation made as part of military science. It's why fortifications on vital communcation routes existed.

I've already mentioned Badajoz, but another example is San Sebastian. This fortified position was garrisoned by about 3,000 troops and delayed Wellington's offensive into France by two months; the troops were all lost, but it brought time for the French to significantly reinforce their positions - from entering France in late June in a state of complete disruption, the French were able to reinforce themselves by about a third and launch on a fresh offensive by the end of July, at which point San Sebastian hadn't even fallen yet.


This is literally what forts are for. They either earn you time, or in assaulting them without prep work the enemy loses heavily.


The thing is, if McClellan does attack the Warwick line, and break through (rather than simply incurring heavy casualties, which could certainly happen when a strong defensive position was assaulted - see, say, Fredericksburg) then there's the possibility for the Union to, by these means, speed up the campaign... but only if the Confederates let them.

This is because the Confederates can, by holding Yorktown until it is reduced, delay the campaign until it's on more-or-less the historical timescale again. That's a Confederate choice.

If you think it's a benefit to McClellan to speed things up, then obviously it's a detriment to McClellan for things to not be sped up. And it's generally considered to be a good rule in war that the enemy is trying to cause you problems.

Alamo comes to mind.

 

[Saphroneth]

Alamo comes to mind.

The Alamo is possibly a little different, because it was built originally as a mission rather than a military fort - the reason I highlight this is that I'm not sure the extent to which it covers a strategic line of communication. It may instead have been more of a place of refuge (that is, locals go into the mission if attacked, and can more easily hold out until relief) or merely put to that use in extremis.

The strategic purpose of Santa Anna may have been to capture the Alamo because it was a place occupied by people defying him or because it could otherwise be a base for raids, rather than because it opened up a strategic line of advance, but I'm unfamiliar with the operational details of the campaign.

 

[JackADriscoll]

The Alamo is possibly a little different, because it was built originally as a mission rather than a military fort - the reason I highlight this is that I'm not sure the extent to which it covers a strategic line of communication. It may instead have been more of a place of refuge (that is, locals go into the mission if attacked, and can more easily hold out until relief) or merely put to that use in extremis.

The strategic purpose of Santa Anna may have been to capture the Alamo because it was a place occupied by people defying him or because it could otherwise be a base for raids, rather than because it opened up a strategic line of advance, but I'm unfamiliar with the operational details of the campaign.

I was thinking of it more how a small determined force can slow a superior one to allow the main body to move

 

[Saphroneth]

I was thinking of it more how a small determined force can slow a superior one to allow the main body to move

That's true, yes - and the Alamo was by no means a purpose built fort. Yorktown was, which makes an escalade assault much harder (since you need to climb a wall that's something more like 20 feet than 8) and means it can resist regular approaches more effectively.

 

[JackADriscoll]

That's true, yes - and the Alamo was by no means a purpose built fort. Yorktown was, which makes an escalade assault much harder (since you need to climb a wall that's something more like 20 feet than 8) and means it can resist regular approaches more effectively.

I was looking at the amero french siege of Yorktown so you feel there are any similarities?

 

[Saphroneth]

I was looking at the amero french siege of Yorktown so you feel there are any similarities?

It's the same fort, and historically speaking the French and Americans bombarded Yorktown with heavy ordnance in order to reduce the defences. The siege there took three weeks all told (two after the opening of the first parallel), but concluded without a final assault as the British defenders decided further resistance served no purpose.

For McClellan, the digging of parallels began on about the 16th or 17th April (from memory) and the guns delayed for a longer time before opening; based on comments I believe this is because of the greater amount of artillery involved (on both sides) and the longer range of the artillery (especially the defenders having rifles).

There's also a bit of a difference in that the French and Americans could advance quite close to the town to open their parallels. The first parallel was apparently only about 2,000 yards long (so not much digging to do and close range), which I suspect helped damage be done quite quickly.

 

[Saphroneth]

Fundamentally speaking when attacking Richmond there are the following kinds of problems.



1) Supply. Do you have a viable means of supply that is sufficiently close to Richmond that you can sustain your army there?


This is a problem that only McClellan really faced, because in solving it (opening up the York and James) he also solved it for everyone else. Grant's operations against Richmond would not have been possible as they were without supply up the York and James.


2) Defensive positions. There are positions which the enemy field army can take that block or impede your progress; that is, these are positions that you have to attack, or otherwise overcome.


In the Peninsular campaign, McClellan faced the following defensive lines:

Big Bethel (he intended to turn this to "bag" Magruder's main force, but Magruder fell back to Yorktown)

Warwick (a flankless position which was overcome after about a month, all told; in the event the line was pierced, much of this delay would have been present anyway owing to the need to open up the York for supply. This position was naturally very strong and had substantial fortifications.)

Williamsburg (a position which McClellan bypassed by flanking up the York; a battle took place, though he didn't actually order one.)

The Chickahominy (not substantially defended by Johnston, mostly imposed delay due to engineering work.)


Burnside faced:

The Fredericksburg position. (This he was unable to overcome.)


Grant faced:

The Spotsylvania position. (He attacked this position in several bloody battles, and was unable to break though it; ultimately he bypassed it with a flanking move. It is not as physically strong as the Warwick line at least, on account of lack of river or 20 foot parapets.)

The North Anna position. (He bypassed this position with a flanking move.)

The Cold Harbor position. (He attacked this position in bloody assaults, and was unable to break through it; ultimately he bypassed it with a flanking move to the James.)



3) The enemy field army, which can attack you. This is as distinct from the enemy holding a fortified line and refers to a pitched battle or Confederate attack; in general such attacks are not simply intended to do damage but to render the line of operations untenable.


McClellan faced two such attacks, Seven Pines and the Seven Days. He successfully defended against the smaller army (Seven Pines) but was pushed away from Richmond by an army larger than his own in terms of regiments and in comparable measures of strength (it cut him off from his then-current source of supply - it didn't just hit McClellan in the face until he retreated). He was, nevertheless, in a good position to continue operations against Richmond.


Hooker faced one such attack, at Chancellorsville. It defeated his army at substantially inferior odds, and he had to abandon his offensive.


Grant faced one such attack, which is similar to Chancellorsville. Grant was able to continue his offensive.


4) The Richmond forts themselves, which require siege work. Certainly in 1864 the defences are stronger than in 1862, but it is my understanding that Richmond proper had some fairly significant fortifications in 1862 (the 17 numbered forts were complete by Feb 1862, albeit not well armed at that time), and in 1864 the defences were strong enough that (garrisoned by most of Lee's field army of the time plus the local defenders) they held out until starved out; in 1862 I would venture to suggest that the defences (garrisoned by most of Lee's field army of the time, which was about the same size in November and much larger in June) could probably amplify the capacity of the defenders to resist enough that siege works are preferred.


This only really applies if a substantial part of Lee's field army is defending them, though.



Now, the reason why I went to the trouble of outlining this is that in November 1862 almost none of those things is going to be able to stop or even significantly delay McClellan. Lee can try and defend the North Anna position against McClellan at bad odds, but McClellan had something of a tendency to just manoeuvre around an enemy blocking position if he could (without the costly and time-consuming attacks first) and Lee's historically planned movements in early November entail his moving SW; it's quite possible this was to rail to the North Anna position from Gordonsville, or he could have been intending to go all the way to the Richmond defences.


Alternatively, Lee could attempt a pitched battle where he attacks McClellan, but again the odds will be bad.


The supply situation's greatest single obstacle is how McClellan gets from Warrenton to the point he's in supply south of the Rapidan/Rappahannock, possibly from Port Royal. Normally this would be difficult, but the reason is because of the Confederate field army; absent their interference McClellan can march to Port Royal. Even if he moves to Fredericksburg his command pattern would obviate the Fredericksburg position as a defensive line.



What this means is that, given Lee's historical plans to retreat to Gordonsville and his calling Jackson to join him through Swift Run Gap, it is simply unlikely that there is anything that could stop McClellan short of the Richmond defences. He won't run into a geographically strong, flankless defensive line at Culpeper, and Lee's movement to Gordonsville prevents him defending the Rapidan; McClellan can move to Port Royal and supply from there and from Aquia, then move south, and there is no place Lee can post himself where he can block McClellans movement south in a way that cannot be flanked.

 

[Saphroneth]

During October 1862, McClellan was told to give his plan for an offensive, and his initial plan (as told to Halleck) was to invade the Shenandoah, going after Lee's army directly. His specific objective was Winchester, and he planned to do this because he would be able to either force a battle with Lee's army or force Lee out of the northern part of the Shenandoah - and either outcome was of benefit. If he forced Lee out of the lower Shenandoah, it was no longer the case that Lee could invade the North the moment McClellan moved away from the Potomac.

This plan was neither approved or rejected, but during this period Halleck and Lincoln both tried to persuade McClellan to opt for a different plan - a plan to move south on the east side of the Blue Ridge mountains.

Lincoln's reasoning was that doing it this way would let McClellan move to Richmond before Lee could get back there, and thus take Richmond without any need for a fight.
Halleck's reasoning was almost directly opposite, arguing that doing this would help protect Washington from a Confederate army on the Rappahannock. (Note that this army did not actually exist.)

I am not actually sure why neither man simply ordered McClellan to take the eastern route. They had the authority to do so, but instead the only order actually given to McClellan was to submit his plans for approval.


In any case, the deadlock was broken in late October when McClellan opted to follow the "eastern" plan - and, unlike his original offensive plan, this got approval within the day. At this point McClellan began bridging the Potomac; on his move south he took pains to operate his corps so that he had a significant force advantage (in reality) at any point where a battle might break out. For example, AP Hill's strong six-brigade division was on the western side of Snickers Gap, and McClellan moved to take the gap on 2nd November with both 2nd and 5th Corps available if a fight developed; meanwhile DH Hill's strong division was south of there, at Upperville (on the eastern side of the Blue Ridge) and 1st and 9th Corps were deployed so as to be available if DH Hill moved towards the Union army in concert with AP Hill.

On the following day, 5th Corps held Snickers Gap to block AP Hill, while 2nd and 9th Corps concentrated against DH Hill, driving him back over the Blue Ridge without need for a fight, and on the 4th of November 2nd Corps occupied Ashby's Gap while 9th and 1st Corps moved south.

On the 5th, 9th Corps took Manassas Gap, while 1st Corps siezed Warrenton.

Consequently there are "jobs" for at least four corps during the advance - three corps holding a gap each, and a fourth to take Warrenton. This defines the force which has to be over the river to make the historical advance possible while blocking Confederate interference


It's possible that those four corps could have been moved so as to be over the river more quickly, with better time and motion. I don't argue that McClellan's movements were optimal. But of those corps, one (5th) was covering part of the upper Potomac against the possibility that Lee was going to invade the Union again, and this corps began moving to cross the river starting on the 29th (it reached the crossing place on the 30th, spent some time resupplying to cover the supply deficiencies of the previous month, then was marching south from the 1st of November onwards having crossed the river.)

That same bridge was in use for 2nd Corps before 5th Corps crossed, and they crossed effectively consecutively. What this means is that it looks like to get those four corps over the river and moving south you need to speed up all the operations at Harpers Ferry (meaning 2nd Corps has to cross earlier to clear the bridge earlier), and you also need 5th Corps to be able to move away from the Potomac sooner.

Historically what freed 5th Corps up was confirmation that Longstreet - who had been at Martinsburg for the previous month, within a day's march of the Shepherdstown fords and not much further from Williamsport - was moving south. This confirmation came late on the 28th, after Longstreet broke camp the same day.



Part of the reason why I've outlined this is to make clear what at least some of the constraints on McClellan's movement south were. In the event, he could use 5th Corps (and then 6th) because Lee was abandoning the possibility of threatening a renewed invasion of Maryland, but this change of posture by Lee happened only once McClellan had already begun moving.

Absent this, for his manoeuvres McClellan would have had to rely on having only three corps available in Loudoun Valley, plus a reinforcement column out of Washington promised to him, and after events of March, May, June and July we can perhaps see why McClellan would be a little leery of believing in such promises - but he was on the move anyway while he couldn't necessarily rely on 5th or 6th Corps.

I sort of wonder if McClellan's intent was to provoke that reaction by Lee, so he could have the troops he needed to do the tasks he was going to need them for, but that's impossible to prove one way or another.



But another part of the reason is to outline why Lincoln's suggestion - that McClellan could march all the way to Richmond before any substantial part of Lee's command could block him - doesn't really work. The time taken to cross two corps over a river, nose-to-tail, is about three days simply because of the length of the various columns of wagons (without any allowance for resupply etc.) and Lee started Longstreet moving at a point when only one of McClellan's corps was even south of the river. At that point, over half of Lee's army (the whole of Jackson's corps, plus Walker's division that would be part of Longstreet's corps) was already closer to Culpeper than any part of McClellan's army, and they'd been in those positions pretty much since mid-October. The other half of Lee's army (Longstreet) was about 1.5 marches (15 miles) further from Culpeper than McClellan's most southerly divisions on the morning of the 28th - and on the morning of the 28th, all but 9th Corps were still north of the Potomac.

What this means is that there is no component of McClellan's army which can get to Culpeper, from a movement starting on the morning of the 28th, than most or all of Lee's army.


So at the time McClellan launched on his move south, he was anticipating the possibility of having to fight at least half of Lee's army, if not all of it - either in the Loudoun Valley or at Culpeper in a blocking position. In the event, Lee made a mistake, which is that he moved Longstreet to Culpeper (and got there first by a considerable margin, because he didn't have to manoeuvre, wait for trailing corps or advance to contact and could just route-march) but left Jackson in the Valley. This would have been a good move had McClellan left his flank open to raid his wagon columns as he moved south, but McClellan effectively covered his flank by blocking the mountain gaps and so Jackson had nothing to raid.

The true magnitude of Lee's error doesn't really manifest until about the 6th or 7th of November, though, because this is the point at which McClellan's army is now supplied (out of Washington) and within striking distance of Culpeper. It is now impossible for Jackson to raid McClellan's supply lines - there's the Bull Run mountains and a whole separate corps in the way, even if he could march forth from the Blue Ridge in that direction - and the only safe means by which Jackson can join with Longstreet is through Swift Run Gap, which is what Lee is telling him urgently to do.

Jackson isn't moving, though, whether because of personal preference or massive supply problems that would ultimately take him weeks to resolve (since, either way, he didn't move for another couple of weeks).

This means that Lee's movements - and the way in which McClellan has operated his own corps, so as to avoid giving Lee an opening to exploit rather than getting himself strung out trying to win a foot-race to Culpeper - have created the situation where Jackson is unable to support Longstreet, and Longstreet is unable to fight McClellan's army by himself. Lee showed a marked reluctance to try, in fact, preparing to retire to Gordonsville.


This is not a good situation for the Confederates to be in, because:

- McClellan was moving south, and was willing (we know this) to attack most of the Confederate army at Antietam with at least three quarters of his own. Here he is facing half the Confederate army and his own army is much stronger than at Antietam, while he knows he inflicted heavy casualties at Antietam.

- Lee was going to get out of the way rather than fighting McClellan at those odds.

- With the Rapidan effectively undefended, McClellan can either swipe at Gordonsville or move to Fredericksburg. Going for Gordonsville gives Lee a choice between separating Jackson even more thoroughly from Longstreet (by moving S/E) or moving west to reunite with Jackson through Swift Run Gap - and the latter means that there's literally nothing between McClellan and Richmond but distance.

- By moving to Fredericksburg, McClellan can get himself in supply south of the Rapidan, and from there outflank (without needing to fight) any Confederate defensive position short of Richmond.

- Lee simply has no good solution to this. He needs Jackson to unite with him to be able to fight a pitched battle with McClellan (i.e. one where the majority of both sides are actually involved in the fighting), he has no means to effectively generate a manoeuvre victory (he can't knock out McClellan's supply lines) and there's nowhere he can force McClellan to attack over a strong geographic defensive position.

 

[DanSBHawk]

Well, it's not automatically "throwing away". It's only throwing away if they cannot be evacuated, and that requires the Union to be able to interdict the York even at night (to prevent the Confederates from evacuating in steamers at night).

But let's say McClellan does this in as efficient a manner as possible - that is, he is an "ideal" general, within the bounds of what you think is possible, against a reasonably capable enemy. He breaks through at the Redoubts on April 6 and encircles Yorktown, but Magruder withdraws north up the Peninsula with most of his force and garrisons about 3,000 men in Yorktown.


How soon can McClellan gain control of Yorktown, in your view, and how does he do it? You've indicated that you think besieging it would make McClellan look silly, so is that genuinely his only option, or is there some other way to do it?

I'm not interested in creating hypothetical scenarios. The fact is that there is no evidence that Lee considered leaving a garrison at Yorktown in the event of an evacuation of the Peninsula.

 

[Saphroneth]

I'm not interested in creating hypothetical scenarios. The fact is that there is no evidence that Lee considered leaving a garrison at Yorktown in the event of an evacuation of the Peninsula.

There is certainly every evidence that Magruder was going to do that in the event of a retreat from the Warwick line (in that he said so), and furthermore, there is every reason that doing so would be very much to the Confederate advantage.

To do as you say Lee was going to do - to abandon Yorktown before it had been invested, let alone besieged - would be to give the Union an enormous advantage, in the form of as much as a month of time.

 

[DanSBHawk]

There is certainly every evidence that Magruder was going to do that in the event of a retreat from the Warwick line (in that he said so), and furthermore, there is every reason that doing so would be very much to the Confederate advantage.

To do as you say Lee was going to do - to abandon Yorktown before it had been invested, let alone besieged - would be to give the Union an enormous advantage, in the form of as much as a month of time.

The order from Magruder does not have any context as to what situation it would apply. There is no evidence that Lee instructed Magruder to leave a Yorktown garrison in the event of abandoning the Peninsula. Lee was obviously issuing Magruder instructions. We know that from the two communications instructing Magruder to not get cut off on the Peninsula. Lee didn't say a word about leaving behind 3000 troops.

 

[Saphroneth]

The order from Magruder does not have any context as to what situation it would apply.

Yes it does. It says to do it if they were forced to retire under any circumstances. It would apply in any situation where they were forced to fall back.

 

[Saphroneth]

We know that from the two communications instructing Magruder to not get cut off on the Peninsula. Lee didn't say a word about leaving behind 3000 troops.

One of them is talking about Magruder being instructed not to get cut off on the Peninsula by a waterborne movement up the York or James, and abandoning Yorktown would materially make the Union's job of cutting Magruder off by a waterborne movement easier. What's the other?

 

[Saphroneth]

But @DanSBHawk, I want you to answer this simple question.

What problem does it cause McClellan for Lee to abandon Yorktown without a siege? Or, conversely, what advantage does it give Lee to abandon Yorktown without a siege, that is worth a whole month? Or even two weeks?

 

[DanSBHawk]

Yes it does. It says to do it if they were forced to retire under any circumstances. It would apply in any situation where they were forced to fall back.

And yet the confederates abandoned Yorktown without leaving a garrison. And if it was so important to leave a small garrison in the event of abandoning the Peninsula, then the confederates would have left a garrison on May 3rd in order to slow down the federal advance. They did not leave 3000 troops in Yorktown. So much for "under any circumstances."

 

[DanSBHawk]

But @DanSBHawk, I want you to answer this simple question.

What problem does it cause McClellan for Lee to abandon Yorktown without a siege? Or, conversely, what advantage does it give Lee to abandon Yorktown without a siege, that is worth a whole month? Or even two weeks?

I'll repeat... there is no evidence that Lee wanted to leave a sacrificial garrison at Yorktown. There is simply no need to speculate about scenarios that are not supported by the evidence.