Corp structure

[atlantis]

1 Was the Two-division Corp structure the optimal force structure for a Corp.
2 With a division strength of 10,000.

What do you all think is the optimal number of Divisions and division strength.

 

[35th MA InfRegt]

If he was trying to copy a European army, I actually wonder if it was the British - he did, after all, have Patrick Cleburne in his army. I don't think it had technically been formalized at this point but British informal practice was, to my understanding, binary corps (though they were quite small).

Then again, if he'd been copying essentially any European army he'd probably have included cavalry at the corps level. So maybe not.

The British had only limited experience with the corps-mostly confined to the Napoleonic Wars-and Wellington scarcely used them except nominally. If Bragg is trying to imitate anybody, it is likely Napoleon who more or less invented the corps as a concept. Other European powers copied the French practice of designating a multi-division formation as a corps but they didn't necessarily adopt an identical organizational structure. Of course, the American versions-especially Union-were a pretty watered down imitation of a Napoleonic corps. Some Union corps were scarcely worthy of the name.

 

[Saphroneth]

The British had only limited experience with the corps-mostly confined to the Napoleonic Wars-and Wellington scarcely used them except nominally.

True, but like I say, British practice (formalized not long after this point) was binary corps, so if you're looking for why Bragg might adopt such an unusual structure then it's not a terrible one - we know Cleburne was importing other British military-cultural practices.

Bragg did not fight at full strength at Perryville. Polk was missing a division. Plus Kirby Smith's forces.

I don't think I claimed he did; my point was more that Bragg doesn't always have binary corps and in fact you can argue that the only battle where he has exclusively binary corps is the first half of Chickamauga.

 

[atlantis]

DH Hill was difficult but IMHO Lee made a mistake in not making him a Corp commander. ANV structured into 3 two division front line Corps led by Jackson, Longstreet, DH Hill and a reserve Corp led by A P Hill plus a 2 division calvary Corp led Stuart would have provided Lee operational flexibility with capable commanders and given AP Hill time to adjust to handling Corp duties [stress seem to agitate whatever chronic illness he was dealing with].

 

[BCD]

What I'm getting at is mostly that I want to flag up that Bragg didn't necessarily have an iron law that he always used binary corps, because he doesn't in most of his actual battles and the organizations fluctuate over time as well. My understanding for example is that when DH Hill takes over the 2nd Corps it has three divisions (Stewart, Cleburne, Breckinridge) and only becomes binary with the reorg after Bragg abandons Chattanooga.

As mentioned, Hill briefly had five divisions, but that was because a) Bragg was throwing reinforcements into his sector as they arrived to fend off the expected Union blow north of Chattanooga, and b) Buckner hadn't yet arrived to absorb the newly-arrived divisions. Bragg was obviously willing to improvise - as when he attached McCown's whole division to Hardee on the eve of Stones River - but battlefield expedients are different from formal structure, where he clearly preferred two-division corps.

To that point, he restructured the AoT to a 3+1 two-division model before evacuating Chattanooga, and kept it more-or-less the same until after Chickamauga - IIRC Johnson's division was scraped together right before the battle from a few stray brigades that had just rejoined the army from Rome and Atlanta. There were no triangular corps at McLemore's Cove: Hindman was tasked to cooperate with Buckner, but that was only an accident of which divisions were on hand when the opportunity arose.

Then during the Chattanooga phase of the campaign Hardee's corps is square (Cheatham, Hindman, Buckner, Gist) of which triangular present in late Nov/Dec, and Breckinridge is also square (Cleburne, Steward, Bate, Stevenson)

True enough. Makes me wonder if his successful employment of two wings on the 20th didn't convince him to abandon his preference for smaller corps.

 

[BCD]

Bragg likely wasn't imitating the Prussians. The Prussian Army of that period was not particularly well-regarded and American knowledge of its organizational structure was probably limited. So, I doubt that was the model Bragg adopted.

Good point. My mind went there because I knew Hardee spent time in France, but the French preferred three divisions. If there was any European influence, Saph is likely correct that it was the British.

 

[35th MA InfRegt]

True, but like I say, British practice (formalized not long after this point) was binary corps, so if you're looking for why Bragg might adopt such an unusual structure then it's not a terrible one - we know Cleburne was importing other British military-cultural practices.

I would like to know precisely when the British first adopted the corps-binary or otherwise-as a peacetime formation. My understanding is that various mobilization schemes were drawn up well after the Crimean War period-beginning in the 1870's if I recall correctly-which would allows corps to be founded in time of war, but none are actually stood up in peacetime until about 1901. The so-called Broderick Army Scheme introducing the corps was a political controversy of the time. And note too, the British Army was not using the corps in any of their wars, certainly not the Crimea, the Indian Mutiny or even the South African War at the turn of the century. I doubt Cleburne had any specialized knowledge about the corps organization that wasn't already available to any student of war who was reasonably familiar with the Napoleonic Wars.

 

[Saphroneth]

I would like to know precisely when the British first adopted the corps-binary or otherwise-as a peacetime formation.

It depends what peacetime means. There wasn't a permanent one, but the British Army in this period did a lot of manoeuvres and my understanding is that the regulations promulgated in 1863 (which is what defines the binary corps) are formalizing existing practice, which means of course that people would need to know about it in order to do it.

(Example of the composition of a British army corps laid out in the 1860s):

Army equipment

books.google.co.uk

12 infantry regiments sounds tiny, but they're all very full-up regiments by US standards. 16,000 combatants is small but within the bounds of ACW corps.


The probable cause for this is that the corps would be used in homeland defence, which is the situation that the British expect to use very large numbers of troops like the militia and the volunteer corps. That's the situation in which the higher levels of organization would actually be necessary.

I will point out though that the "Army Corps" sent to South Africa for the Second Boer War essentially was the "1st Corps" under the mobilization scheme.

 

[35th MA InfRegt]

It depends what peacetime means. There wasn't a permanent one, but the British Army in this period did a lot of manoeuvres and my understanding is that the regulations promulgated in 1863 (which is what defines the binary corps) are formalizing existing practice, which means of course that people would need to know about it in order to do it.

(Example of the composition of a British army corps laid out in the 1860s):

Army equipment

books.google.co.uk

View attachment 591170
12 infantry regiments sounds tiny, but they're all very full-up regiments by US standards. 16,000 combatants is small but within the bounds of ACW corps.


The probable cause for this is that the corps would be used in homeland defence, which is the situation that the British expect to use very large numbers of troops like the militia and the volunteer corps. That's the situation in which the higher levels of organization would actually be necessary.

I will point out though that the "Army Corps" sent to South Africa for the Second Boer War essentially was the "1st Corps" under the mobilization scheme.

That does clarify the issue as these regulations clearly suggest that paper schemes for the mobilization of a corps in the British Army were in existence rather earlier then I was aware of. Still, as yet we don't seem to have any real evidence that Bragg was actually aware of them.

Yes, an "Army Corps" is stood up under the mobilization schemes and sent out to serve in the Second Boer War. I believe it was redesignated as the Natal Field Force and temporarily served as the defacto theater-wide army headquarters under Buller until Lord Roberts took over as Commander in Chief. I suppose you could call the Natal Field Force as an expeditionary corps under another name. I *think* Roberts' command was designated as the South African Field Force but I can stand to be corrected on that point. The British, for one reason or another, simply didn't care to use the corps designation in expeditionary warfare even if the scale of combat would have justified it.

 

[Saphroneth]

That does clarify the issue as these regulations clearly suggest that paper schemes for the mobilization of a corps in the British Army were in existence rather earlier then I was aware of. Still, as yet we don't seem to have any real evidence that Bragg was actually aware of them.

Oh, absolutely. It happens that British is binary and so I thought, hey, maybe Cleburne was the conduit of information, but I think more likely is just that two divisions is as small as you can get a corps.

Yes, an "Army Corps" is stood up under the mobilization schemes and sent out to serve in the Second Boer War. I believe it was redesignated as the Natal Field Force and temporarily served as the defacto theater-wide army headquarters under Bullet until Lord Roberts took over as Commander in Chief. I suppose you could call the Natal Field Force as an expeditionary corps under another name. I *think* Roberts' command was designated as the South African Field Force but I can stand to be corrected on that point. The British, for one reason or another, simply didn't care to use the corps designation in expeditionary warfare even if the scale of combat would have justified it.

Personally I suspect the issue is that what you need for the British to accept something as a corps is a situation where there are at least four divisions operating such that there is operational benefit to splitting them as part of a single army, instead of using them in a combined army or in separate armies. For example I think a Trent war might see the use of corps in the defence of Canada, not just because of the scale but because of the ability to attach local Canadian troops to them, but I'm not sure of that and they might in practice end up as distinct armies.

 

[OpnCoronet]

However, those Army Corps were usually the strength of a full division. Hence Burnside and Meade both "doubled up" their corps into grand divisions, or wings, each of which was essentially an army corps.

The issue is that legally only POTUS can create or disband an Army Corps. No matter how weak they got, they were legally still an Army Corps. At the other extreme, 13th and 14th Army Corps were, when created, really armies and so were divided in wings until sense prevailed.

But Confederate divisions were over strength in comparison with Union Divisions?

 

[Saphroneth]

But Confederate divisions were over strength in comparison with Union Divisions?

I admit I'm not sure how that's a "but". Sometimes Confederate strengths are what we would call "double strength" in comparison with Union ones, but that's at points when the Confederate divisions are 6-bde corps by another name.

I struggle to think of an example of a Confederate division that's truly overstrength in the sense of being more than 10,000 men for a 3-brigade formation (while many Union divisions very early in the war were, in fact, over 10,000 men PFD for 3 brigades). However, the Confederates seem to have had a smaller number of divisions total in their main field army, resulting in those divisions being less understrength as divisions - that is, the Confederate divisions are close in strength to a "proper" division because they have fewer of them.

The armies at Gettysburg have enough infantry that we would divide them into ~6-7 (Lee's) or ~9-10 (Meade's) full strength infantry divisions of about 10,000 men PFD. Lee in fact has 9 (so his divisions are, on average, at 2/3 of nominal strength) while Meade in fact has 19 (so his divisions are, on average, at 1/2 of nominal strength).

You could say that Lee's units are overstrength compared to Meade's, but I think that incorrectly normalizes the idea that 5,000 men is the expected size.

 

[OpnCoronet]

I admit I'm not sure how that's a "but". Sometimes Confederate strengths are what we would call "double strength" in comparison with Union ones, but that's at points when the Confederate divisions are 6-bde corps by another name.

I struggle to think of an example of a Confederate division that's truly overstrength in the sense of being more than 10,000 men for a 3-brigade formation (while many Union divisions very early in the war were, in fact, over 10,000 men PFD for 3 brigades). However, the Confederates seem to have had a smaller number of divisions total in their main field army, resulting in those divisions being less understrength as divisions - that is, the Confederate divisions are close in strength to a "proper" division because they have fewer of them.

The armies at Gettysburg have enough infantry that we would divide them into ~6-7 (Lee's) or ~9-10 (Meade's) full strength infantry divisions of about 10,000 men PFD. Lee in fact has 9 (so his divisions are, on average, at 2/3 of nominal strength) while Meade in fact has 19 (so his divisions are, on average, at 1/2 of nominal strength).

You could say that Lee's units are overstrength compared to Meade's, but I think that incorrectly normalizes the idea that 5,000 men is the expected size.

So a Confederate Div. had more Regiments and brigades than the Unions?

 

[Saphroneth]

So a Confederate Div. had more Regiments and brigades than the Unions?

On average, yes. To take an example, at Gettysburg my count is that the Union has about 235 infantry regimental organizations (meaning about 12 regiments per division) and most divisions are triangular, with 3 brigades; the Confederates have 37 brigades spread over 9 divisions (so the average division is square, not triangular) and 172 regiments in 9 divisions (so the average division has 19 regiments). The average Confederate division is organizationally stronger.

Note that picking Gettysburg happens to be just after the sudden reduction in Union strength from a lot of expired enlistments, but it's how the AoP existed for the second half of 1863. The same sort of pattern has also emerged at Antietam, where the two sides have about the same number of brigades and regiments on the field at the end of the 17th (39 bdes and 181 regiments for the Confederates, 43.5 bdes and 189 regiments for the Union) but the Confederates have 9 divisions (average 4.5 bdes, 20 regiments) and the Union has 16 divisions (average 2.7 bdes, 12 regiments).

 

[67th Tigers]

But Confederate divisions were over strength in comparison with Union Divisions?

Well, let's remember that the concept of a "Corps" didn't exist until October 1862. The Confederate Congress passed a law on 18th September authorising the President to appoint Lt Gen's as GOC's of army corps. When Lee was asked for recommendations for the new rank, he recommended Longstreet, Jackson and AP Hill. Davis' reply isn't preserved, but Lee then replied only Longstreet and Jackson then. It's believed DH Hill was the problem, as he had seniority over AP Hill. As soon as DH Hill was reassigned, Lee made preparations to reorganise into three corps, even before Jackson was killed.

Seven officers were originally made LG's, with two each in the main eastern and western armies (Longstreet and Jackson, Polk and Hardee), with the other three commanding larger commands that became independent corps (EK Smith in East TN, Holmes in the Trans-Mississippi, and Pemberton on the Mississippi). The independent corps weren't really a set size.

In the ANV, before the authorisation of corps, a lot of large divisions had been created, many of which contained two divisions. The large divisions endured a while. Eventually, Lee reorganised things as he wanted, rather than accepted what was. Lee went with 4 brigade divisions as standard, with each corps having an extra brigade assigned to one of the divisions, but which was usually detached to the reserve.*

Bragg did much the same, organising the army into two corps each with 2 divisions of 4 brigades. At Stone's river he had an extra brigade and a small division attached, which he added to other formations.

Ultimately, a standard rebel division (by 1863) was 4 brigades vs 3 for a Federal one, but the rebels hadn't mind consolidating understrength regiments and brigades to maintain a certain strength. The meant the brigades were often quite a bit larger. In 1864, the AOP kept consolidating understrength brigades as well, and I think brigades then were directly comparable in size.

* At Gettysburg, two of Pickett's brigades were left behind, accounting for anomaly.

 

[67th Tigers]

It depends what peacetime means. There wasn't a permanent one, but the British Army in this period did a lot of manoeuvres and my understanding is that the regulations promulgated in 1863 (which is what defines the binary corps) are formalizing existing practice, which means of course that people would need to know about it in order to do it.

(Example of the composition of a British army corps laid out in the 1860s):

Army equipment

books.google.co.uk

View attachment 591170
12 infantry regiments sounds tiny, but they're all very full-up regiments by US standards. 16,000 combatants is small but within the bounds of ACW corps.

The 8 batteries had three distinct organisations. They were paired into battalions, and each division had a battalion with additional small arms reserve ammunition. Another two batteries were the reserve battalion, without a small arms ammunition reserve, and the last two were horse artillery, attached to the cavalry brigade.

At the time of the Boer War, there were three army corps, each of 3 divisions of two brigades, but the 3rd Army Corps was mixed regular reserves. The regulars at home were reorganised into three corps (1st-3rd) of 2 divisions (1st-6th) of three brigades (1st-18th) in 1901, and in 1914 they had an extra independent brigade (19th) at home. The IV Corps was raised by regulars returned from overseas garrisons (7th and 8th divisions, 20th-25th brigades). The neatness didn't last, as to incorporate the TF, initially each Corps got a TF division, and then to incorporate the new army and more TF, each Corps became a regular, a TF and a new army division...

 

[Wizard of Cozz]

Well, let's remember that the concept of a "Corps" didn't exist until October 1862. The Confederate Congress passed a law on 18th September authorising the President to appoint Lt Gen's as GOC's of army corps. When Lee was asked for recommendations for the new rank, he recommended Longstreet, Jackson and AP Hill. Davis' reply isn't preserved, but Lee then replied only Longstreet and Jackson then. It's believed DH Hill was the problem, as he had seniority over AP Hill. As soon as DH Hill was reassigned, Lee made preparations to reorganise into three corps, even before Jackson was killed.

Do you have the citation about AP Hill being recommended before Jackson's death? I'd like to read that.

Seven officers were originally made LG's, with two each in the main eastern and western armies (Longstreet and Jackson, Polk and Hardee), with the other three commanding larger commands that became independent corps (EK Smith in East TN, Holmes in the Trans-Mississippi, and Pemberton on the Mississippi). The independent corps weren't really a set size.

In the ANV, before the authorisation of corps, a lot of large divisions had been created, many of which contained two divisions. The large divisions endured a while. Eventually, Lee reorganised things as he wanted, rather than accepted what was. Lee went with 4 brigade divisions as standard, with each corps having an extra brigade assigned to one of the divisions, but which was usually detached to the reserve.*

Bragg did much the same, organising the army into two corps each with 2 divisions of 4 brigades. At Stone's river he had an extra brigade and a small division attached, which he added to other formations.

Ultimately, a standard rebel division (by 1863) was 4 brigades vs 3 for a Federal one, but the rebels hadn't mind consolidating understrength regiments and brigades to maintain a certain strength. The meant the brigades were often quite a bit larger. In 1864, the AOP kept consolidating understrength brigades as well, and I think brigades then were directly comparable in size.

* At Gettysburg, two of Pickett's brigades were left behind, accounting for anomaly.

All of Lee's corps were usually divisions of 4,4,5. Though sometimes brigades got detached as you note with Pickett's division. When Second Corps gets gutted at Spotsylvania they go with 3,3,4, though some of these are consolidated brigades of technically two bigades.

 

[Wizard of Cozz]

The 8 batteries had three distinct organisations. They were paired into battalions, and each division had a battalion with additional small arms reserve ammunition. Another two batteries were the reserve battalion, without a small arms ammunition reserve, and the last two were horse artillery, attached to the cavalry brigade.

At the time of the Boer War, there were three army corps, each of 3 divisions of two brigades, but the 3rd Army Corps was mixed regular reserves. The regulars at home were reorganised into three corps (1st-3rd) of 2 divisions (1st-6th) of three brigades (1st-18th) in 1901, and in 1914 they had an extra independent brigade (19th) at home. The IV Corps was raised by regulars returned from overseas garrisons (7th and 8th divisions, 20th-25th brigades). The neatness didn't last, as to incorporate the TF, initially each Corps got a TF division, and then to incorporate the new army and more TF, each Corps became a regular, a TF and a new army division...

I wanna say that the British had the extra layer of the battalion. Whereas during the civil war a battlaion was just a regiment that didn't have the full compliment of companies.

 

[67th Tigers]

Do you have the citation about AP Hill being recommended before Jackson's death? I'd like to read that.

I read about this first in Harsh ISTR. Davis wrote Lee on the 28th September, asking for formal recommendations. On the 2nd October, Lee formally recommends Longstreet and Jackson, with the caveat that AP Hill is the next best. My memory was there was an earlier letter, but I cannot find it right now, so may be misremembering. I do remember the argument was DH Hill's seniority was the issue, but I cannot remember where I read that...

 

[OpnCoronet]

On average, yes. To take an example, at Gettysburg my count is that the Union has about 235 infantry regimental organizations (meaning about 12 regiments per division) and most divisions are triangular, with 3 brigades; the Confederates have 37 brigades spread over 9 divisions (so the average division is square, not triangular) and 172 regiments in 9 divisions (so the average division has 19 regiments). The average Confederate division is organizationally stronger.

Note that picking Gettysburg happens to be just after the sudden reduction in Union strength from a lot of expired enlistments, but it's how the AoP existed for the second half of 1863. The same sort of pattern has also emerged at Antietam, where the two sides have about the same number of brigades and regiments on the field at the end of the 17th (39 bdes and 181 regiments for the Confederates, 43.5 bdes and 189 regiments for the Union) but the Confederates have 9 divisions (average 4.5 bdes, 20 regiments) and the Union has 16 divisions (average 2.7 bdes, 12 regiments).

So in combat, in one on one confrontations, a Union corps is at a disadvantage in numbers, in relation to a Confederate Corps?

 

[Saphroneth]

So in combat, in one on one confrontations, a Union corps is at a disadvantage in numbers, in relation to a Confederate Corps?

At certain times, yes - in the East, that is. This mostly applies from the time the Confederates formally organize corps in the East (October 1862, from memory - before then Confederate corps are informal, though still larger than the binary Union ones) to the point where the Union discontinues 1st and 3rd Corps in the East and fills the other three up (March 1864, at which point Union corps are now much bigger on average).