McClellan's alternatives

Saphroneth

Lt. Colonel
Joined
Feb 18, 2017
Split from another thread to avoid clogging it up. Basic intent is to discuss the nature of McClellan's campaigns and what options he had.

I also want to avoid the 'McClellan-Go-Round' and note that this is largely an opinion/hypothetical thread so I will keep it brief. So, here's my list (opinion):
Ball's Bluff (McClellan in command of units present but not present himself) - Major US Defeat (in a small battle);
Prior to Peninsula Campaign (McClellan ordered to attack CS at Manassas and Centreville but doesn't do so and instead suggests Urbanna Plan. CS J E Johnston shifts forces to a new defensive line so Urbanna Plan is nullified;
Peninsula Campaign (conceived by McClellan and under his command) had the goal of capturing Richmond but ended with McClellan withdrawing the army from the Peninsula and included the battles of orktown [US 60K, CS 13K - US does not attack], Seven Pines/Fair Oaks [US 34K, CS 39K - CS attacks with end result of draw/stalemate], Seven Days [US 115K, CS 92K - CS attacks and US ends Peninsula Campaign];
Sharpsburg/Antietam [US 87K, CS 38K - Technical US Victory] where McClellan should have crushed the CS army (given his vastly superior numbers) but to me only managed another stalemate as Lee withdrew his army in good order and McClellen did not pursue them.

[Note: Force numbers mentioned above are approximate as I did not go into detail and generally sourced those numbers from Wikipedia.]


By all means start another thread, that's up to you and it may be best or we'll drift too far from the OP. My vote in a hypthotical situation "If not Grant, then who?" is Hancock and yours is McClellan.

As I said in my earlier post "Force numbers mentioned above are approximate as I did not go into detail and generally sourced those numbers from Wikipedia" so they were only rough guides but I think the end results stand.

In terms of the Urbanna Plan, I disagree that "Lincoln killed the plan". Lincoln didn't like it but he did approve it [see link] but the Plan was null and void once Johnson moved his defensive line.


So I'll be looking at these in a moment.
 
Okay, so Urbanna first.

The sequence of events has to be looked at closely.


The first step is that McClellan outlines the Urbanna plan. He also has a few other landing options, including Fort Monroe, which he considered the slowest.

At Lincoln's request McClellan then moves into the Shenandoah (reoccupying Harpers Ferry), which was a condition Lincoln put on the amphibious movement. That is to say, Lincoln required McClellan to do the Shenandoah operation before he would approve an amphibious movement.
This is done, and it's the cause for Johnston moving back from Centreville.

Lincoln asks for a vote by McClellan's division commanders (on the 8th of March) and they support Urbanna eight to four.

In the next few days Johnston pulls back from Centreville, and Lincoln promotes the four division commanders who dissented from Urbanna to corps command.

He then asks for another vote on Urbanna (evening of the 12th to morning of the 13th of March) and those corps commanders vote against Urbanna and substitute in the Fort Monroe plan.


The move by Johnston back from Centreville to the line of the Rapidan didn't actually render Urbanna a non-starter, because while it meant Johnston had more scope to respond (as opposed to the original situation where he'd have no recourse) his response would still have to be swift - in fact, swifter than the historical reaction to the Peninsular plan - in order to prevent McClellan from opening up the York river within a few days of landing.
What kills Urbanna is firstly the move into the Shenandoah which caused Johnston's retreat (which is something Lincoln ordered) and secondly the vote by the corps commanders on 12-13 March (which, again, is at Lincoln's instigation).

So yes, Lincoln was definitely involved in the Urbanna plan being cancelled, and it's hard to see his actions as anything except for trying to get rid of it by any means possible. If the changed situation had been enough to provoke a revote he would just have had all the original commanders vote again, but he instead selected people who'd not liked Urbanna.

I cannot see a course of action McClellan could have taken which would have left Urbanna viable, given the actions of others. I can see several ways in which different courses of action by Lincoln could have left Urbanna viable.
 
Further, I'd like to note that had Heintzelman not made his ill-advised (and against implied orders) demonstration against Magruder on 27th March then Lee would not have ordered Johnston to have 5 brigades ready to make a strategic movement. As it was, Johnston resisted sending troops to the Peninsula and delayed as much as possible. It's possible that McClellan really could have stolen a march on Johnston.
 
Addressing the Peninsular campaign would take a very long time, but the short version is that McClellan designed the plan to use twelve divisions (4 corps of 3 divisions) plus army level troops, and when the campaign began this was the understanding. He then lost four of those twelve divisions from his command (Blenker and 1st Corps), and only ever got two of them back (Franklin and McCall) while the enemy reinforced; despite this, he was gaining the heights over Richmond by the end of June 1862 and if he'd had two more divisions we know where he would have put them and it would have blocked Lee's movement in the Seven Days.

The strength of Lee's army in the Seven Days is not precisely known, but he had about 2,150 to 2,200 companies of all types with his army (215-220 regiments of all arms) counting the Richmond garrison; McClellan had about 170 regiments/1700 companies by the same measure, which means that with his strength at 105,000 regulation PFD with his army we should expect Lee's strength to be about 133,000 regulation PFD. Lee's strength may have been less than that, but it was greater than McClellan's total strength with his army.


It is hard to see how McClellan could possibly have retained that many men with his army. He did everything he was told to by Lincoln, and he lost the divisions anyway; whenever someone evaluated if he needed reinforcement they agreed he did, but then didn't actually send them.
 
13 divisions - Mansfield was supposed to take a division out of Fort Monroe as well.

Of the 13 slated divisions, 5 were removed and 3 added back afterwards.
 
Lincoln sent a fact finding mission, and they reported McClellan had been right:

"Providence Forge, May 14, 1862
ABRAHAM LINCOLN, President

We [Seward and Chase] think that you should order whole or major part of General McDowell's, with Shields, up the York River as soon as possible, and order Whyman's flotilla up the James River. General McClellan moves to White House tomorrow morning.

WM H. SEWARD"

Lincoln still wasn't happy and eventually consulted Scott; and he told Lincoln McClellan had been right all along.
 
13 divisions - Mansfield was supposed to take a division out of Fort Monroe as well.

Of the 13 slated divisions, 5 were removed and 3 added back afterwards.
Fair point, yes; I'm not sure if that extra one was meant to be in the Urbanna plan, but I did indeed not count it.
 
The next one to look at is Antietam, first with the numbers.

I am of course aware that the Antietam numbers that are usually quoted give McClellan a bit more than a 2:1 advantage; however, this advantage is not real. It is the result of different numbers being used for different armies.


McClellan's numbers for his army are based on the strength of his army PFD, and without accounting for straggling (which was severe, in both armies); the commonly quoted numbers for Lee's army are based on the strength of his army in effectives, sometimes effective infantry, and after straggling had taken place.

If we look at Lee's army before the start of the campaign (i.e. after Second Bull Run), it comes to roughly 75,000 PFD (which is in the same category as McClellan's 87,000 PFD in units on the field on the 17th). This number for Lee includes one brigade which was not on the field on the 17th, though McClellan's number includes some fresh regiments who were not on the field on the 17th so this is more or less a wash.

If we look at Lee's army as it was observed marching through Frederick, the combat echelon of Lee's main body was "not more than 64,000 men" (which discounts the baggage train) and took 16 hours to go past; that part of DH Hill's division which marched through Frederick (four brigades) was estimated at 8,000. One brigade of DH Hill, Walker's division and Stuart's cavalry are not included in this measure, and this means that the "not more than" 72,000 men observed marching through Frederick does not include about 13,000 men; while this is probably a higher estimate than PFD it does not conflict with the idea of an army of around 75,000 men PFD (while it does conflict with a much smaller army size).

If we look at how many regiments Lee's army contained, we see that he had about 180 infantry regiments on the field at Antietam; McClellan had about 190. McClellan's regiments were on average a little stronger because his army included some very green regiments, but not enough stronger on average to account for this.

If we look at Lee's post-battle returns and add on the casualties of the Maryland Campaign, even the immediate post-Antietam return which is badly disrupted and the admitted Confederate casualties (which are low) imply a strength at Antietam of 36,400 (post-Antietam return, 22 September) + 5,700 (first cavalry strength) + ~800 (first artillery strength) + ~13,500 (admitted casualties) for 56,400; using the later strengths where the Confederate army has recovered (to 64,273 on 10 October) and the higher total casualties derived from checking things like the number of men buried on the field and the number of men captured and exchanged produces up to 81,000, though this double counts several thousand wounded who had returned to the colours by October 10.

Thus, estimates in the same category as McClellan's 87,000 all imply Lee had over 55,000 men, and most of them suggest a number over 70,000.


If we instead look at the number of effectives actually on the field, we still find that Lee's strength is higher than the usually quoted total because the usual number for Lee is not properly checked. Going through every regiment and brigade for the Confederates produces around 39,000 effective infantry on the field, plus enough artillery and cavalry to push the strength up to about 47,000 (though this number has a large range of error on it) - but doing the same thing for the Union produces a number around 57,000, again with a large range of error, because the Union army straggled just as badly as the Confederate one. (1st Corps got almost exactly 2/3 of their theoretical PFD into line of battle, as assessed at the time; most other formations were similar.)



Thus, at Antietam McClellan does not have an overwhelming numerical advantage - he has some numerical advantage, but it's made up of fresh ("green") infantry, some of them so new they've never fired their muskets. All of Lee's men are veterans.
There is no consistent reading of the numbers at Antietam which produces the sense McClellan outnumbered Lee 2:1.
 
Before reaching Antietam itself, I'm first going to look at the more fluid operational state of the Maryland Campaign. This is the point at which McClellan has reached Frederick Maryland (which he does on the 13th).



This is what the Lost Orders said, plus what Lee had actually done, and the opportunities that it opened for McClellan.

Note by the way that SO 191 was issued on Tuesday 9 September; consequently "Friday" is September 12. McClellan recieves the orders September 13.


Special Orders, No. 191
Hdqrs. Army of Northern Virginia
September 9, 1862




  1. (missing)
  2. (missing)
  3. The army will resume its march tomorrow, taking the Hagerstown road. General Jackson's command will form the advance, and, after passing Middletown, with such portion as he may select, take the route toward Sharpsburg, cross the Potomac at the most convenient point, and by Friday morning take possession of the Baltimore and Ohio Railroad, capture such of them as may be at Martinsburg, and intercept such as may attempt to escape from Harpers Ferry.
  4. General Longstreet's command will pursue the same road as far as Boonsborough, where it will halt, with reserve, supply, and baggage trains of the army.
  5. General McLaws, with his own division and that of General R. H. Anderson, will follow General Longstreet. On reaching Middletown will take the route to Harpers Ferry, and by Friday morning possess himself of the Maryland Heights and endeavor to capture the enemy at Harpers Ferry and vicinity.
  6. General Walker, with his division, after accomplishing the object in which he is now engaged, will cross the Potomac at Cheek's Ford, ascend its right bank to Lovettsville, take possession of Loudoun Heights, if practicable, by Friday morning, Key's Ford on his left, and the road between the end of the mountain and the Potomac on his right. He will, as far as practicable, cooperate with General McLaws and Jackson, and intercept retreat of the enemy.
  7. General D. H. Hill's division will form the rear guard of the army, pursuing the road taken by the main body. The reserve artillery, ordnance, and supply trains, &c., will precede General Hill.
  8. General Stuart will detach a squadron of cavalry to accompany the commands of Generals Longstreet, Jackson, and McLaws, and, with the main body of the cavalry, will cover the route of the army, bringing up all stragglers that may have been left behind.
  9. The commands of Generals Jackson, McLaws, and Walker, after accomplishing the objects for which they have been detached, will join the main body of the army at Boonsborough or Hagerstown.
  10. Each regiment on the march will habitually carry its axes in the regimental ordnance—wagons, for use of the men at their encampments, to procure wood &c.


so191-jpg.jpg


(maps from the GCACW series, which show the roads quite well, with my own additions)




As of when the orders are captured, it's Saturday. The orders expired on Friday, but because Harpers Ferry has not yet fallen they are a fairly good predictor (though not perfect) of Confederate positions.
Given that McClellan knew DH Hill left Frederick on the 11th, and assuming that he knew there was no extra division or so knocking about not included in the orders, the below is what McClellan could reasonably predict Lee's positions to be in red (along with the true positions, which are slightly different and where different are in orange).

Note that while the cavalry is not marked on this map, this is because McClellan was actually in contact with it already - Stuart's cavalry was holding the Cactotin passes as of noon on the 13th, and Jefferson Pass is not taken until near sundown.



so191_13-jpg.jpg




Before continuing, stop a moment and work out how you think there is an opportunity to destroy Lee's army.

As I see it:

Jackson's force and Walker's force (totalling 16 brigades all told) are impossible to catch as things stand. They have a free and clear escape route back south and to get at them means crossing the Potomac.

Longstreet's and DH Hill's forces (9 and 5 brigades respectively) are north of the Potomac and can be attacked, but they have a clear escape route to the west via Williamsport or Shepherdstown.

McLaws' force (10 brigades) is vulnerable so long as Harpers Ferry holds out, as this pins them in the Pleasant Valley if South Mountain can be forced. This is about a quarter of Lee's force and is the component that is actually vulnerable.

With this in mind, what McClellan actually does is:


so191_14-jpg.jpg





There's only two suitable roads to use, with two thirds of McClellan's army trying to squeeze through Frederick (thus a lot of the delay) and the attack at South Mountain begins around 9AM on the 14th.

To my mind this is about as good as it gets in terms of being able to exploit Special Order 191. Lee reacts quickly to try and make the situation better, and what's more Lee actually gets really lucky with Harpers Ferry surrendering when it does (he'd ordered Jackson to abandon the siege, but Jackson ignored orders) but the simple fact is that 3/4 of Lee's army is either safe from McClellan's attack or has a clear line of retreat to safety.




What this means to me is that McClellan's choices in this period in terms of where he sends bits of his army are pretty close to optimal. There's no manoeuvre I can see which makes better use of the situation at the time.
 
So at Antietam itself, because it's a battle instead of an operational campaign, McClellan's options are actually a bit more limited. In an operational campaign there's the scope to impose your will on the manoeuvres (within limits), but with a battle - especially a short one like Antietam - there are definite limits on what a commander can actually do. One of the main things they can do is decide where to route various units as they arrive, or commit them from reserve; another thing is that they can outline to their corps commanders the plan to be followed. It's not really the role of an army commander to micromanage, though, because at that point they've lost the ability to coordinate their whole army.

With that in mind, McClellan's primary constraints at Antietam are the geography and the nature of the arrival of his forces.

He has the following options for when to make his first attack (assuming that he can't make major attacks with the same troops on two succssive days - his army is fragile, and much of it was recently routed or is very new.) Those are, effectively:

- On the afternoon of the 15th.
- On the morning of the 16th.
- On the afternoon of the 16th.
- On the morning of the 17th.
- On the afternoon of the 17th.
- On the 18th.

Attacking on the afternoon of the 15th is basically not possible. McClellan has only two divisions which have arrived yet, and he's actually outnumbered by Lee about 2:1.

On the morning of the 16th, McClellan is opposed by Longstreet's force (9 brigades), DH Hill (5 brigades), Jackson (4 brigades) and Ewell (4 brigades), for a total of 22. He has Sykes and Richardson available by the Middle Bridge, and they can get into action that morning; 1st Corps is around the Upper Bridge, and can also cross. 2nd Corps is still some miles away.
This is not good odds, notwithstanding that it's foggy.

By the afternoon, the fog has burned off, and an attack is at least going to take place in reasonable weather. 2nd Corps is still arriving and 12th Corps is behind them, and it would be possible to launch an attack which got 1st Corps, 2nd Corps and Sykes involved (for a total pre-straggle PFD of 38,000*). For Lee, meanwhile, Walker has arrived, bringing Lee up to 42,500 pre-straggle PFD.
*
5,000 (Sykes) +
1st Corps 15,000 (Antietam strength plus casualties from South Mountain, minus 16th Maine detached)
2nd Corps 18,000 (Antietam strength, minus 145th PA not yet arrived)

An attack on the 16th is thus at roughly even odds, and is a bad idea given how the force ratio is shifting.

What McClellan actually elects to do is to attack in the morning of the 17th, by which time 12th Corps and 9th Corps are available. Since he intends to launch a dawn attack Morell's division and Franklin's corps are not predicted to be available when the attack actually launches, but they will arrive over the course of the morning and be available to get involved if the need arises; thus McClellan commits to attack when he has 64,000 PFD available to attack and 82,000 PFD all told (both pre-straggle strength exclusive of cavalry). It happens that Lee has had McLaws and Anderson arrive overnight and so his strength has risen to about 61,000 pre-straggle PFD, but this means the attack is at parity before counting the extra units arriving in good time to be used; McClellan can't know for sure if McLaws and Anderson have arrived of course.

Attacking in the afternoon of the 17th brings Lee up to about 68,000 pre-straggle PFD exclusive of cavalry as AP Hill arrives, and means McClellan has all 82,000 to hand, but this actually shifts things in Lee's favour.

And an attack on the 18th means Lee still has 68,000, but McClellan is bolstered by another 7,000 (Couch) giving him 89,000. If Humphreys' exhausted division that arrives in the afternoon can get involved this goes up to 96,000, but this is probably not feasible.


Based on the numbers alone, the best option is to attack on the morning of the 17th. At this point McClellan can expect to have a 34% numerical advantage assuming all fighting takes place before AP Hill arrives; the next best option is on the 18th with Couch present, which gives a 31% numerical advantage, and any other option is worse than these. Attacking earlier also constrains the nature of the attacks.


What McClellan actually did was to correctly read the terrain. There are three bridges:

The Upper Bridge is in no-man's-land and can be crossed en masse. There is room to deploy before attacking.
The Middle Bridge has enemy troops overlooking it on defensible ground. There is not room to deploy.
The Lower Bridge is congested, but lets out into an area where the enemy can be cut off from the Potomac. One corps (9th) is in position to reach it in time for an attack in the morning of the 17th without diminishing the other attacks.

McClellan thus holds his centre lightly (one division up and his reserve division back), diverts 9th Corps to the lower bridge, and puts everything else over the upper bridge - counting 1st, 2nd, 12th and 6th corps plus the cavalry the bridge probably sees about 40,000 effectives cross it (60,000 pre-straggle PFD) and McClellan's intent is for a single coordinated blow which would make it perhaps the largest single coordinated attack of the war; as it is, the attack is "merely" three corps-level blows which cause Lee to commit his entire reserve to stabilize the situation.
McClellan's intent was for this to be the first step of a manoeuvre sur le derriere - forcing his enemy to commit his reserves in one place, then sending in an attack (9th Corps) in another, and finally putting in the reserve over the middle bridge if it has not been needed elsewhere. The attack by 9th Corps is also badly managed, taking hours longer than it should.

The fundamental point here is that the concept of the attack is sound, and that it did not really ask the impossible of the corps commanders and the men involved. The issues are related to execution, and those probably stem mostly from the thrown-together nature of the army which had no time to do exercises and where some corps commanders were being assigned while the army was already marching through Maryland; for example it should not have taken a corps numbering over 13,000 men (pre-straggle PFD) almost half a day simply to capture a weakly held bridge.


McClellan's alternatives at Antietam at the army commander level thus consist of:

- Date of attack. Morning of the 17th is drawn for best choice with the 18th, though part of his logic was presumably that he had no way of knowing how long the enemy would remain (if Lee had been afraid of being destroyed he could have withdrawn south of the Potomac overnight).
- Attack plan. The plan McClellan historically used is pretty good, and while not perfect (especially in hindsight) it's got an operational concept behind it and the first phase did what it was supposed to. The only real alternative is just to stack up a really big hammer by sending in even more troops on the right flank at once (and have no push over the lower bridge), though the lower bridge would still need to be covered.
- Commitment of reserves. It is possible there are places where different reserve management could have resulted in a better outcome.
- Going over and handling one of the moving parts himself. Very difficult to do in practice because a corps commander is supposed to be able to execute basic orders, and for a lot of the critical period things are happening on both ends of the field at once while reinforcements are also arriving and need direction (if McClellan is supervising Hooker he's not supervising Burnside and vice versa). If there were three McClellans then that would help, of course...


After the fighting on the 17th, most of McClellan's army was too tired to fight on the 18th (it's not exactly common in the Civil War for a commander to launch major attacks with the same troops on two successive days). On the 19th McClellan does conduct a general advance, but the enemy has largely withdrawn over the ford.
 
Post Antietam, things get a bit more screwy.

At this point there are broadly speaking three places where the Potomac can be crossed into the Shenandoah, which is where Lee is. Those are:

North at Williamsport, which is where Lee had sent his cavalry just after the battle.
In the middle at Boteler's Ford, just by Sharpsburg.
South at Harpers Ferry.


McClellan has two fresh-ish corps in hand (6th and 5th) plus Couch, and he sends first Couch and then 6th Corps to Williamsport to block Lee from re-entering the North. 5th Corps attempts a pursuit over the Potomac, with 12th Corps marching down to retake Harpers Ferry and the rest of the army at Sharpsburg; Lee sends a quarter of his army (AP Hill and Ewell, 10 brigades out of 40 and about 45 regiments out of 180) to stop-punch 5th Corps at Shepherdstown.
McClellan then shifts his weight to his right, since 12th Corps has reoccupied Harpers Ferry, and moves his main body (all except 5th and 6th Corps) to the town over the course of the 22nd and 23rd ready to enter the Shenandoah.

Halleck has previously told McClellan he will get 11th Corps and asks where, and McClellan says that as he plans to enter the Shenandoah he will want 11th Corps sent to Knoxville (near Harpers Ferry).
McClellan's movements make sense for his planning to re-enter the Shenandoah, such as ordering the building of a bridge to cross into the Shenandoah, and there is no reason to believe he did not intend to do so; his leaving two corps on the upper Potomac is to prevent Lee from slipping past him to invade the North.

His alternatives in how to do so would be to send his main force to cross at Williamsport or at Boteler's Ford, but crossing at Harpers Ferry offers a greater chance for victory:

plan_27th.jpg



Moving from Williamsport gives a chance to push Lee down the Valley; moving from Harpers Ferry gives a chance to cut Lee off or force him to retreat precipitately. Moving solely from Boteler's Ford would give Lee the chance to either fall back south or defend the line of the Opequon, and is also problematic from a supply perspective (notwithstanding that, as it transpires, Lee's army was close enough to substantially defend the Shepherdstown crossings if need be).


Starting on the 26th, Halleck effectively forbids McClellan from moving by denying him the funds needed to rebuild bridges until his plans are agreed upon. McClellan does send his plans to Halleck for approval, but Halleck stonewalls (refusing to grant permission to rebuild the bridges McClellan needs to supply his army in the Shenandoah).

While it is a slight simplification of a long period, it would be fair to say that the situation of "Halleck has forbidden McClellan from crossing the Potomac, either directly or by witholding approval of funds for bridge building" persists for the next month. Halleck simply never gives approval to McClellan's plan of entering the Shenandoah, and it's only when McClellan offers a different plan (of moving south through the Loudoun Valley) that Halleck gives approval - his approval coming the same day.


It is possible that McClellan could have moved faster and thereby pursued Lee, but if so then the evidence suggests that the reason this would work is not because "it would be more militarily correct" but because "it would be moving too fast for Halleck to interfere". This isn't a failing in McClellan's generalship, in other words, but a failing in the political relationship at Washington and of Halleck - if Halleck had given approval for building bridges etc., there is no reason McClellan could not have been crossing into the Shenandoah by the end of September at the latest.

An alternative is that McClellan could have accepted the Loudoun plan straight away, but (quite apart from ongoing supply difficulties which would have made this very risky) the reason why the switch to the Loudoun movement happens when it does is shifting force ratios.

McClellan was promised 30,000 reinforcements if he went by Loudoun, but no more than 15,000 if he went into the Valley. Based on his contemporary strength numbers and the need to cover the upper Potomac, this means that the options were:

Option one - go into the Valley
McClellan can use all his corps (5th and 6th making subsidiary thrusts coordinated with the main one) plus 15,000 troops' worth of reinforcement.
Option two - take the Loudoun plan
McClellan has to leave three corps along the upper Potomac (covering Boteler's Ford, Williamsport and Harpers Ferry) and gets 30,000 troops' worth instead of 15,000.
Since the average strength of a Federal corps at the time was on the order of 15,000, option two leaves McClellan 30,000 troops weaker even assuming all the reinforcement promises are fulfilled; if they're not fulfilled (and this had happened in the past) McClellan could well end up outnumbered by Lee taking the Loudoun option.

In mid-late October meanwhile the Potomac has risen, and so the fords on the upper Potomac are largely blocked. McClellan can use 5th and 6th Corps if he takes the Loudoun movement, and so he no longer has to worry about leaving so many men on the upper Potomac; he marches south and conducts the Loudoun movement well, but is fired.


There are probably alternatives here for how McClellan could have better conducted himself, but his decisions are at least in keeping with military principles.
 
The next one I'm going to look at is Yorktown, which in the post to which this thread responds was summarized as "US 60K, CS 13K - US does not attack"

This is going to need a look into the instantaneous situation at several moments.



As of late March, when the first two to three Union divisions were on the Peninsula, the Confederates were not occupying the Yorktown or Warwick line (along the Warwick river). They were occupying Yorktown itself, but were largely in place on an advanced line, and McClellan's intent was to build up forces at Fort Monroe while trying to maintain the illusion that he was going to attack somewhere else - then land troops (1st Corps, with Franklin's division landing first) between the advanced line and Yorktown, in order to cut off the majority of the local Confederate forces.


Pen_Plan.jpg

While this is not the only option, it is at least a reasonable option - since it took several days for each set of shipping to go back and forth and there was never enough shipping to move more than a corps at a time, building up troops in the controlled area south of the Big Bethel line and then aiming to trap the majority of Magruder's forces is a workable approach.
The alternatives are basically about how many troops are built up on the Peninsula before sending 1st Corps, or landing 1st Corps at Fort Monroe itself (and not bothering with the landing), or landing 1st Corps on the York-Rappahanock Peninsula (i.e. in Gloucester County).

Unfortunately, the Union troops already on the Peninsula alerted Magruder to their presence with an ill-advised demonstration (27-28 March). This meant Magruder pulled back to the Warwick line, and it was time for McClellan to ditch this plan and come up with another new one. (The Peninsular plan had only been the actual plan for about two weeks at this point, as before this time it had been Urbanna as the primary.)


McClellan pushed forwards shortly after he personally arrived, and after rushing forwards more troops to the Peninsula. As and when he advanced, McClellan had five divisions available to do so (six had landed, but the sixth was garrisoning Newport News and was in any case not available for the field) plus the infantry reserve under Sykes. On Magruder's side, on the day McClellan reached the line he'd already been reinforced by several regiments, and more troops were en route.

In terms of attacking on arrival, there are two options. Option one is to order an attack straight away, on the 5th; this is basically going in with both columns in attacks along the roads they're already marching.
Option two is to make an attack on the 6th, and there's a bit more scope for finesse and choosing your spot here.

The strength on these dates is slightly hard to determine; what I'm going to use is effectives for the Confederates, because we have those numbers - albeit the numbers for the end of the siege (which are lower than they would be at the start, because of skirmishes and sickness), but they are broken down by regiment and battery and we can track when the regiments and batteries arrived.

On the 5th, Magruder has 1,119 effectives in Gloucester Point, and the rest of the line is garrisoned by 18,353 men (of which about 1,700 is cavalry and about 2,700 is artillery, leaving about 14,000 infantry).
On the 6th, with the arrival of the brigades of Early and Rodes, Magruder's strength in the rest of the line (exclusive of Gloucester Point) has swollen to 23,900 (almost all of the increase is in infantry).
So no, not 13,000 by any measure.

McClellan's strength is not given in the same category, but in PFD he did have about 60,000; in effectives this would be a little over 50,000.

More importantly, though, on the 5th what McClellan actually ordered was for both columns to attack.
To Keyes (leading the left flank column) “Ride back as fast as you can, and tell General Keyes to attack with all his force if only with the bayonet.”
To Porter (leading the right flank column) “Attack with all your forces as soon as you arrive.”

What happened was that both approaching columns were plastered with artillery at long range, and the corps commanders demurred from launching a "hasty" attack.

On the 6th McClellan's forces start spreading out looking for a weak point, and discover that the fortified line is continuous. No attack is launched on the 6th, but it's still at the point where you'd need to "attack all along the line and look for a weak point" and this would result in being slaughtered all along the line - the only ways over the Warwick for most of the line are narrow dams, with obvious potential to slaughter the attackers.


Heavy rain (a storm) then starts and continues until the 10th or so, at which point (on the 11th which is the first dry day) the defenders are up to 33,000 men in the main line.


So what are McClellan's alternatives? I can't really see one that isn't "ram your troops into a prepared killing zone and hope the enemy runs out of bullets"; a few days later a potential weak spot had been identified, but doing this sophisticated engineering analysis takes time.
 
He has the following options for when to make his first attack (assuming that he can't make major attacks with the same troops on two succssive days - his army is fragile, and much of it was recently routed or is very new.) Those are, effectively:

- On the afternoon of the 15th.
- On the morning of the 16th.
- On the afternoon of the 16th.
- On the morning of the 17th.
- On the afternoon of the 17th.
- On the 18th.

I know that you know, but it should be noted the McClellan did attack on the afternoon/evening of the 16th driving the Rebels from the East Wood in preparation for the large scale attacks of the 17th.
 
I know that you know, but it should be noted the McClellan did attack on the afternoon/evening of the 16th driving the Rebels from the East Wood in preparation for the large scale attacks of the 17th.
That's correct; I was referring to the main attack (the full clash of the armies) but it's worth clarifying, so thank you.
 
A lot of the problems with the Peninsula - not all of them, but a lot - resulted from how the movement was planned with certain expectations by McClellan (that is, the amount of force he would have and the amount of naval support he would have) and then once things changed they did so in a way that took away a lot of his options and a lot of his freedom of action.

What I'm going to quickly look at here is whether McClellan could have taken alternative actions so as to avoid this loss.



For the sake of clarity, I will reiterate that the decision which instituted the Peninsular Campaign as the preferred campaign choice was not a decision by McClellan - who considered Urbanna preferable, the reason being the potential for the reduction of Yorktown to cause a delay of weeks to on the order of a month. Instead it was the result of a vote by McClellan's corps commanders, those being McDowell, Sumner, Heintzelman and Keyes, and the decision was adopted on the 13th of March.
The substance of this decision is:

13th March

HEADQUARTERS ARMY OF THE POTOMAC,

Fairfax Court-House, March 13, 1862.

A council of the generals commanding army corps at the Headquarters Army of the Potomac were of the opinion-

I. That, the enemy having retreated from Manassas to Gordonsville, behind the Rappahannock and Rapidan, it is the opinion of the generals commanding army corps that the operations to be carried on will be best undertaken from Old Point Comfort, between the York and James River, upon Richmond, provided-

1. That the enemy's vessel Merrimac can be neutralized.

2. That the means of transportation sufficient for an immediate transfer of the force to its new base can be ready at Washington and Alexandria to move down the Potomac, and

3. That a naval auxiliary force can be had to silence or aid in silencing the enemy's batteries in York River.

4. That the force to be left to cover Washington shall be such as to give an entire feeling of security for its safety from menace.

Unanimous.

II. If the foregoing cannot be, the army should then be moved against the enemy behind the Rappahannock at the earliest possible moment, and the means for reconstructing bridges, repairing railroads, and stocking them with material sufficient for the supplying the army should at once be collected for both the Orange and Alexandria and the Aquia and Richmond Railroads.

Unanimous.

NOTE.- That, with the forts on the right bank of the Potomac fully garrisoned, and those on the left bank occupied, a covering force in front of the Virginia line of 25,000 men would suffice.

KEYES.
HEINTZELMAN.
McDOWELL.

A total of 40,000 men for the defense of the city would suffice.

SUMNER.


In addition to this, Keyes later claimed (in a 7 April letter) that before giving his assent to the plan he had consulted with Gustavus Fox, assistant secretary of the Navy, to the effect that a naval auxiliary force could (in principle) be had for helping reduce the batteries on the York (i.e. Yorktown and Gloucester Point).

It is possible that Keyes was lying about this, of course. But it is information Keyes was willing to put in writing in early April and should therefore roughly match with what he was saying in mid to late March; we know from diaries of various corps commanders that there were several meetings between the Army and the Navy subsequent to this point, and we also know from a letter by Gustavus Fox, writing to the local navy commander in March (on the 24th) that the idea of bombarding Yorktown (phrased as "knocking down the town") was something the Navy was aware the Army was asking for. Consequently there is at least reasonable grounds for McClellan to expect naval co-operation to involve naval bombardment.


The strength of the defenders of Washington, meanwhile, amounted to both "40,000 men total" (Sumner) and "25,000 men, plus garrisons for the forts south of the Potomac and occupying the forts north of the Potomac" (the other three corps commanders consulted). This implies that the garrison needed for Washington was on the order of 15,000 men, though we can also test this.
A full garrison meant enough troops to man the walls for three shifts, while occupation meant enough men to man the walls for one shift. In mid-1863, with the forts now much more extensive than they were in early 1862, full garrisons south of the Potomac took 11,795 and full garrisons north of the river took 14,780. This implies 4,827 men required to "occupy" the forts north of the Potomac in mid-1863, for a total required defences in Washington itself of (less than, as it's early 1862 not mid 1863) 16,722.
This implies that the split of 15,000 for Washington and 25,000 in the field force is correct.


Naval
Given that McClellan had reason to believe (based on the statements of one of his corps commanders) that a naval bombardment had been asked for, it would have been quite understandable for him to simply rely on naval bombardment to reduce Yorktown if the need arose. However, what McClellan actually did was to also set up a contingency plan (specifically, he had a siege train prepared) in case naval bombardment was not forthcoming.
The problem with getting naval support was not (despite later claims) that nobody in the Navy was aware that they might be wanted to bombard Yorktown until at least April, because the letter of the 24th of March indicates they'd already heard of it.

The only real alternative here would be for McClellan to pressure the navy until he had a response in writing, but this may not have been feasible; certainly the contingency plan approach meant he retained options.


Land troops
This one is a little more involved.



The troops removed from McClellan's command came in three tranches (arranged without strict regard for order), those being:

1) The removal of Blenker's division, which was ordered sent to the Mountain Department in late March; Lincoln apologized for the political pressure he'd been under and promised him that it would be the last removal from his command. The justification used for this was that it was to increase the force defending Washington.

2) The removal of 1st Corps, which came after Blenker's division. This was based on a brief prepared by Stanton to the effect that the defences of Washington were too weak, with less than 20,000 men in them; in response to this Lincoln authorized the retention of either 1st or 2nd Corps, and Stanton transferred the (larger) 1st Corps out of McClellan's army.

3) The confirmation that Fort Monroe (i.e. the Department of Virginia) was not part of McClellan's command authority, which also came after Blenker's division. The reason for this one is less clear but appears to result from concerns over the relative seniority of McClellan and Wool; McClellan had intended to pull a field division from the regiments in the Department of Virginia and assign it to General Mansfield.


It has been argued in the past that McClellan should have made his case more strongly to Lincoln to the effect that Washington was already safe. However, it seems pretty clear to me that not only did McClellan more than fulfil the requirements laid out in fact (as in, the amount of troops he was planning to leave fulfilled the requirements) but that the justifications used for the removal of Blenker's division and McDowell's 1st Corps make clear that either Lincoln or those advising Lincoln were willing to use whatever justification of the Washington Defences happened to support their goal of the moment, without consistency.

It is true that the document McClellan produced, which outlined how he was going to defend Washington once all the troops en route had arrived and all the troops he was taking to the Peninsula had left, contained errors; I'm not denying that. But it also did not include all the troops it could have included, and in neither case were the removals based on those flaws - instead they were based on fallacious reasoning which would have been incorrect whether or not McClellan's outline document was correct.


McClellan's definition of the troops available to defend Washington basically consisted of:
- Banks' corps (5th Corps, Army of the Potomac, which included a large cavalry contingent), which numbered 22,703 PFD at the end of March.
- The forces in DC and Alexandria, which combined numbered 20,185 PFD at the end of March.
- The Railroad Brigade (part of the Middle Department), the strength of which cannot be fully determined.
- New regiments which had not yet arrived in the area, which would replace more experienced troops in rear areas behind the covering force and allow those rear-area troops to join the covering force itself.
There was some double counting of some brigades in this assessment. It did not include:
-- the rest of the Middle Department (i.e. the garrison of Baltimore) which combined with the railroad brigade numbered about 14,000 PFD.
-- the Mountain Department, which in March (before Blenker's arrival) numbered 18,298 PFD.

When arguing that Blenker should be detached, the argument made to Lincoln was that the Mountain Department constituted part of the defences of Washington. This would make the amount of troops defending Washington more than 61,000 PFD without the Railroad Brigade or Middle Department, without new regiments and before the addition of Blenker.

When arguing that Washington was inadequately defended, however, the argument made to Lincoln was that (in the opinion of Lorenzo Thomas, who wanted "full garrisons" north of the Potomac as well) Washington was not "entirely secure" because it had a garrison of only about 18,000 men by Wadsworth's count. (This was in conflict with the opinion of the War Board as a whole, which agreed on 27th March that McClellan's arrangements left Washington secure; Stanton used the dissenting voice as the focus of his argument that Washington was not secure).

What this means is that within a couple of weeks Lincoln was convinced to reduce McClellan's force by:
1) The argument that the Mountain Department counted as defending Washington (with the addition of Blenker's division making the Mountain Department about 27,000 strong)
and also
2) The argument that not even Banks' corps counted as defending Washington, let alone the Mountain Department.

As a result of this, the total force counted by someone as defending Washington rose to:
22,700 (Banks' force, always considered part of the Washington Defences by McClellan and counted as such by the War Board in the 27th March discussion)
+ 20,200 (Washington defences and Dept. of Alexandria, self-evidently defending Washington)
+ 33,500 (McDowell's corps, removed ostensibly to help defend Washington)
+ 27,200 (Mountain Department with Blenker's division included, added because it counted as defending Washington)
Plus the railroad brigade
Fot a total of over 104,000 men PFD - i.e. more than 10,000 men stronger than McClellan's field army once 1st Corps and Blenker had been removed.


As far as I can tell, the only way McClellan could have feasibly avoided these detachments, assuming everybody else acted the way they historically did, would be to be in Washington himself so he could argue his own case. It was not a matter of convincing Lincoln because not only did he comply with the recommendations of the corps commanders but Lincoln was convinced of two contradictory things within the space of a few weeks; it was not a matter of errors on his document about how he was defending Washington, because the argument for the removal of 1st Corps didn't hinge on those errors.


Of course, possibly there's an alternative, though McClellan didn't exactly have an enormous amount of time to work them out - what with trying to manage a movement intended to be of about 130,000 men with only a few days to do it in. But it's probably telling that Lincoln then didn't notice that 1st Corps wasn't added to the garrison of Washington, but instead used to bulk out the covering force.
 
Centreville

This is going to be a comparatively quick one. @Quaama said that McClellan was ordered to attack at Centreville but did not.


There are two things to address here. The first is that what Lincoln ordered was:

January 31, 1862

Ordered that all the disposable force of the Army of the Potomac, after providing safely for the defense of Washington, be formed into an expedition, for the immediate object of siezing and occupying a point upon the Rail Road South Westward of what is known of Manassas Junction, all details to be in the discretion of the general-in-chief, and the expedition to move before, or on, the 22nd. day of February next. ABRAHAM LINCOLN



The 22nd of February is a significant date - it's Washington's Birthday - but it's also in the middle of winter, and the directive to do something on that date was basically a propoganda thing.
McClellan's reply was to ask to be allowed to make a turning movement instead, and Lincoln then asked him (on Feb 3rd) to explain why he wanted to do this instead of the much more direct option Lincoln wanted. McClellan's subsequent reply contains the basics of the Urbanna plan, and Lincoln thus rescinded the order of January 31.

So the reason McClellan didn't attack at Centreville was that he felt it was a bad idea and explained why, and Lincoln cancelled the attack order.



The second thing is that Centreville itself is a strong position. The only lines of operation against its right flank are fords over the Bull Run and Occoquan rivers - the Bull Run Bridge had been destroyed - and this was considered chancy, while operating against the left flank to get in behind would involve wagon transport out of Washington curving around on a long and vulnerable route.
Direct attack was, obviously, attacking into defences directly.
It would also be possible to cross the Potomac above Leesburg, but this would at most provoke Johnston to fall back; the Urbanna plan offered the possibility to exploit his position.
 
Seven Pines

This is another quick one, looking at the strength available to Johnston and to McClellan at Seven Pines.

The first thing to point out is that Seven Pines was fought during a period when the Union was spread over the Chickahominy and the Confederates were not. What this means is that the Confederates could pick and choose their targets to gain local superiority, even if they had inferior total numbers.

For example, if we assume for the moment that the Confederates had 100 regiments and they would need 40 regiments to defend the main fortified line from the Chickahominy to the White Oak (if not attacking there), and 10 to defend the Mechanicsville bridges and other methods of crossing the Chickahominy (if not attacking north), then to be able to deploy equal troops to the possible Confederate attacking force would take:

North of the river - possible attacking force is 100 - 40 = 60, so 60 regiments north of the Chickahominy
South of the river - possible attacking force is 100 - 10 = 90, so 90 regiments south of the Chickahominy

Meaning that it would take a 50% superiority in total strength at Richmond (in this hypothetical) to avoid giving Johnston somewhere he could attack at an advantage.

The actual strength available to Johnston during Seven Pines was about 140-150 regiments of all arms (i.e. 1,400-1,500 companies of infantry/cavalry/artillery, of which about 100 companies was the Richmond garrison itself) and McClellan had about the same (split into five roughly equal corps). He placed two north of the Chickahominy (5th and 6th), two south (3rd and 4th), and had his fifth corps (2nd) ready to move wherever an attack took place; 6th Corps was also partly available to move, but the bridges over which they were to move collapsed.

The fact that both men commanded about the same number of troops (and such a large number of companies) means that it's unlikely either force was below 40,000 PFD; we should roughly expect both of them to be more like 80,000 PFD, though this counts the troops which did not actually participate in the fight (on both sides).


More importantly, though, there simply isn't any scope for a counterattack. McClellan's deployments allow him to move troops to counter Johnston's attack, but there isn't an unguarded route into Richmond.
 
Back
Top