"Longstreet over Lee???" Topic

I admit this is just another one of those opinion topics you may or may not be interested in. I think we can all agree that Lee is considered the best battlefield tactician the south had or at least that is the reputation.
I must admit though the more I read about Longstreet the more I am impressed with him and think history hasn't given him the credit he deserves. I am wondering if he would not have been just as good or even better as commander of the ANV?? It seems he was very cool under fire, great tactician, well liked. He seemed to try and keep the casualty count down on his troops when he could, forcing the enemy to attack fortified positions, good ground etc, but I have read several accounts that if he saw a chance to gain the advantage he was willing to attack, take a chance.
Am I way off base here and missing something or do you guys think the same?? Just curious.

Well, in his most notable independent command during the Knoxville Campaign in 1863, he lost the Battle of Fort Sanders and failed against of all union generals…..Ambrose Burnside!

Command the ANV? Better rethink that.

Kim

Let's not forget that Longstreet had a falling out with A.P. Hill in 1862, and with McLaws after Knoxville. He got into a dust up with army command because he tried to maneuver a favorite into acting divisional command. The delay in starting Seven Pines may well have been due to a precedence dispute between Longstreet and Huger. Longstreet wasn't solely responsible for the upheaval in the Army of Tennessee preceding Chatanooga, but he did contribute. Also Longstreet was given two opportunities at independent command. Neither produced favorable results.

Longstreet's overall record as a divisional and corps commander within the ANV was good, but the ANV was better off under Lee. Whether the AoT would have done better if Longstreet had supplanted Bragg before Chatanooga is a closer question.

Lee's reputation is mostly derived from beating incompetent Union generals he knew before the war. The ones who gave up after setbacks and retreated. His major offenses failed disastrously. Everything was "Virginia Virginia Virginia".
After the war, his Lost Cause acolytes slammed anyone who didn't think he was a total genius. Pickett never forgave him, for one. Longstreet was another. I am reminded of the line from "The Duelists". "There are those who say you never loved the Emperor."
I do think that Longstreet could have done a better job.
Statistically, didn't Lee take more Confederate casualties than he inflicted on the Union?

Interesting assessment of Longstreet's leadership during the war prepared as a thesis for the Army's Command College.

PDF link

After the war Longstreet became a Republican and supported reconstruction. This led to many in the South to hate him and his reputation suffered. Jubal Early was one who blacked his name every chance he could. So, this makes it harder to say what kind of commander Longstreet was. He seemed to have a right idea at Gettysburg but, as has been pointed out, he failed badly in the Knoxville campaign.

My feeling was that corps command was Longstreet's limit. Mind you, he might have been the best in the war on either side. Certainly he'd be high on the short list. But army command required different skills, and he didn't shine when he had opportunities.

If I was told to find a replacement for Bragg, I'd start with Hardee.

I read a fairly recent book on Longstreet.

Lieutenant General James Longstreet: Innovative Military Strategist, The Most Misunderstood Civil War General by F. Gregory Toretta (Casement Publishers: 2022).

Toretta calls him "… a brilliant tactician and strategist." and goes on to describe him as "one of only a very few Confederate officers to take the mental leap and prepare to fight the war they were facing, not the war they wished they were fighting."

Although a well written book, it seemed to me there was not enough analysis by the author, just a lot of dependence on Longstreet's and others' writings.

But from all my reading, I think he was one of the very few top-rate Confederate (and Union) generals in the war.

Jim

@Chris, that table on page 77 looks like a combat results table from a 70's board game. I'll have to read it when I get a chance. Thanks.

Longstreet was a superb Corps commander – and to be fair if supported by the Richmond administration he might have been a pretty good ANV commander

I just brushed up on the Knoxville campaign via Wikipedia.
link

It seems that Longstreet was badly outnumbered, had a very difficult supply situation, was unsupported, and Burnsides was actually quite competent.
🤷

I'd go along with your first three points, OFM. But I'd add that he sought out the assignment, quarreled with his subordinates, and wasted men in an assault which couldn't possibly have worked due to inadequate intelligence, despite having a week to plan and a friendly population in Knoxville.

Every losing commander can explain why he shouldn't have been expected to win, but while Longstreet could and did overcome adverse conditions as a corps commander, he doesn't seem to have been able to when operating independently.

Longstreet seems to invoke some strong feelings either for or against. For example, if ACW historian Robert R. Krick read this post, he'd have a heart attack. He was the most anti-Longstreet historian I've ever heard a lecture from.

I personally think very highly of Longstreet and his abilities, but I don't think he ever would have been made commander of the ANV if Lee had died or been incapacitated early in the war. He simply didn't have the rapport with Davis that Lee did. Davis was a very aggressive minded commander in chief and Lee's aggressiveness meshed well with Davis. Longstreet was for being smart about when and where to be aggressive which would not have suited Davis.

Longstreet had a excellent opportunity to cut off Burnside at Campbell Station in the early stages of the Knoxville Campaign. Had he done that, he could have bagged a good portion of Burnside's forces and undoubtedly succeeded in the campaign. But the excellent Union delaying tactics and muddy conditions prevented this. Once that opportunity passed, there wasn't much chance for a successful conclusion.

I heard once that Longstreet would have made a great anvil to Jackson's hammer had Jackson lived. But the only time there was such a situation at Second Bull Run, Jackson was the anvil and Longstreet the hammer. The only other major battles after the Seven Days in which both were corps commanders were Fredericksburg and Antietam and Lee was on the defensive in both.

Compare Longstreet to Jacksons when in independent command. Jacksons was successful at The Valley Campaign, Cedar Mountain, the capture of Harpers Ferry and really his flank attack at Chancellorsville was his idea and executed independently.

Gamertom is correct that Longstreet would not have ever been given command of the ANV if Lee needed replaced. Odds are it would have been Joe Johnson or PGT Beauregard as they were already full generals.

I do believe Longstreet was a competent corps commander, but when Lee reorganized his corps after Jackson's death, he reduced Longstreet's command from 5 divisions to only 3 which is telling.

Kim

I think that it's a bit harsh to judge Longstreet on his very limited experience of independent command. Lee made mistakes in his early (and later) days.

If you take the view that the Confederacy's best chance of winning (by which I mean achieving independence, rather than trouncing the Union) was to exhaust the Union's will to continue the fight, I'd probably take Longstreet over Lee due to the latter's profligacy with the lives of his men.

Thanks for the input guys, very interesting and lots of information. Sounds like my impression was partly correct. He obviously was one of the better ones, may or may not have been up to the task but as we all know, will never know for sure:)
As a side note I didn't bring up Jackson because I feel like his style was very similar to Lee's and with Jackson you would be getting more of the same, perhapes even a more aggressive version??? Plus I have read various reports that Jackson, like many generals was not liked by every one and would not have commanded the same loyalty from both the common soldier and other generals. Happy gaming all!!!

Unfortunately gamer1 we don't have a Wayback machine that we could use to test the hypo. The very act of putting Longstreet in command of the ANV in front of Richmond in the aftermath of Seven Pines is going to cause him to develop differently as a commander than he did commanding a wing and then a corps under Lee. If you look at Lee's ACW performance in the period leading up to him assuming command of the ACW it would be hard to predict you'd end up with the man that lead the ANV from 1862-65. Longstreet was more aggressive in the Seven Days than he claimed to be at Gettysburg and at the end of the war. who is to say that if Longstreet had pushed McClellan away from Richmond in a series of offensive actions he might not have followed Lee's path.

Either way, it wouldn't have mattered. There was simply no way the South was going to win a protracted war— they had neither the infrastructure nor the manpower to do so. The North had the factories and the constant influx of Irish immigrants to resupply their forces both in war material and flesh and blood. The South did not. Lee made the best gamble that could have been made with his invasion of Pennsylvania. It failed.
After that, there was nothing but an inevitable long decline to defeat.
Longstreet would not have changed that. Indeed, there was no military mind in the world (then or ever) who could have changed that.

Wars are like that— typically already decided before they are started, with the one starting them often just not able to see the truth of the outcome the future held in store.

I agree the south really only got one, may be two chance's to have been able to "win" and by win I mean survive in some form. Yes, they were pretty much doomed from the start. That was never really part of my thinking in bringing up the topic, I was just curious if my thinking was correct that may be Longstreet doesn't get the credit he deserves along with Jackson and Lee, thats all. Also, like Bill said, there is no real way of knowing unless you could go back in time and change things to see:) I did admit in my initial it was just a topic to share opinions on. Happy gaming all!!!

Please consider,
Gen. Longstreet was not part of the long planning for the Gettysburg Campaign as he was south with his troops. Gen. Jackson and Gen. Stuart would be looking over maps with Gen. Lee to plan the movement. So it would be expected he was not "100%" with Gen. Lee's thinking.

Actually, Jackson was dead and Longstreet conferred with Lee in mid-May after he returned to the ANV to plan the summer campaign. JEB Stuart pretty much went off and did his own thing during the campaign.

Longstreet advocated for his command to be sent to Tennessee which Lee rejected. After the loss at Gettysburg Longstreet did get his wish and was sent west in the fall which led help secure victory at Chickamauga, but the victory was squandered by Bragg.

Kim

Actually, Jackson was very alive during the winter of early 1963 and reports show he might have really talked to Lee.
'JEB Stuart pretty much went of and did his own thing during the campaign', some believe this was after the planning for the campaign.

Heck, I would take Jubilation T. Cornpone over Lee!

There is a book called "North with Lee and Jackson" about how those two longed to take the war north of the Potomac, preferably into Pennsylvania.

link

"There was simply no way the South was going to win a protracted war— they had neither the infrastructure nor the manpower to do so."

Parzival, I have noticed that protracted wars are not necessarily won by the side with manpower and factories. See for instance the AWI--or pretty much every US war since the Korean Armistice. The weaker side wins by prolonging the war and raising the cost of victory for the stronger side, for whom the war is not an existential struggle. Obviously this is aided by psychological shocks like Saratoga, Yorktown and Dien Bien Phu, but we seem to have lost a number of wars without losing any significant battles. Correlation of forces matters, but so does cost-benefit analysis. I do not say a Confederate victory was ever probable, but it was entirely possible until--I'd say at least the summer of 1863, and arguably into 1864.

Much of what Longstreet proposed made sense. That doesn't mean he could have carried it out, or even that he was the best man to do so.

Robert, you're comparing the wrong sorts of wars. A war fought on distant territory with which neither soldier nor citizen has any ties or cultural similarity or moral connection simply isn't comparable to the circumstances of the ACW.
At best, the US in the Vietnam War was a disconnected opportunist effort seeking other goals than anything having to do with the Vietnamese people or their government. There was no investment in or real need for the political victory, leaving the citizens of the US persuadable that the war had no connecting purpose to themselves or their lives or needs.

The ACW is entirely different. There were direct ties between the North and South— whole families wound up fighting on opposite sides. The cultures were, for the most part, substantially the same— European Protestant Christianity, Western philosophy, free-market capitalism— even the language, minus some regional dialects and idioms— were entirely the same. Both sides had inherent and significant political and economic stakes in victory. The Union could not just "walk away"— the citizenry understood and had a need for victory. Thus, simply delay was unlikely to (and did not) produce a civilian-based demand for abandonment of the effort. The US could leave Vietnam and wind up with nobody caring all that much. The Union could not have abandoned the South in anything like the same manner.

The same is true of Great Britain in the AWI. The general populace of England really didn't care about the rebellion in America. Yes, the culture, language and faiths were largely the same, but the political connections on the side of England really weren't there. They were distant "owners" of the American vineyard who had never visited it, worked it, or profited from it, and really didn't care what happened to it. What was the point of war in America, in the end, as far as the people of England were concerned? Keeping the King's name on things? Who really cared for that? There were more pressing issues in Europe. It was a costly war, overseas, against a people with whom the English themselves had no real quarrel (why should they?). The loss endangered the English not a bit. Nobody cared about Saratoga or Yorktown except the government and the newspapers.

So I put forth that your comparisons are faulty. It mattered to the people of the United States (including many hundreds of thousands in the South) that the Union remain intact. Lee's gamble— which was to surround DC and force a peace on the US government— was the only one with half a chance. The South could not pull off the "distant delay" strategy of the AWI or the Vietnam War, because it wasn't distant; it was next door… or even just in the next room.

And I say that history itself proves me right. By the end of the war, the ability to fight a long delay was over… indeed, it died at Gettysburg as much as Lee's gamble did. My proof? It didn't happen. I am quite convinced that Lee knew of it— of course he did; it was Washington's strategy! Every general of the war who graduated West Point knew that strategy; they studied it throughout their tenure there! But I give Lee credit for realizing what worked against distant England would not work against the next-room North. (Forrest suggested it before the surrender at Appomattox; Lee wisely dismissed it.) The delay would not produce victory; only an even worse defeat.

So I contend that it was always so— the South had no chance of victory, either in 1861, 1862, 1863, or 1864. It just took them five years to finally admit it.

Good argument, Parzival--but not, I think, conclusive. We have, I think, very different notions of proof. For me, "it didn't happen" isn't proof it couldn't have happened, and "Lee didn't try it" isn't proof it wouldn't have worked.

Yes, you can find divided regions and families--but for the most part, we're looking at different cultures and even different lines of descent. Postpone a northern victory long enough, and northern voters face a war which is killing their sons and raising taxes, without having much to do with land or the price of wheat.

Agreed that the odds favored the north, especially after the secessionists fumbled the early rounds of interstate and international diplomacy, but I don't think the Confederate chances were zero. I'm not even convinced that the capture of Washington was their best chance. (I'd have said capture of a US field army.) But absent a paratime machine, all we have is more or less informed opinion.

There's never a paracop around when you need one.

The only way for the Confederacy to have won was to convince the Union that the war wasn't worth fighting.
In my not so humble opinion, Lee caused more confederate casualties than Union casualties. I read that on the internet so it must be true.

Might be true, OFM. But it isn't necessarily relevant. If the Confederacy was willing to accept higher percentage losses to establish its independence than the Union would accept to regain control and/or abolish slavery, there could be a zone in which a southern general could take greater losses and still be winning. In fact, a southern general might need to inflict a certain level of Union losses regardless of his own casualties.

I don't really know how well losses or percentage losses in a war serve as predictors of winners and losers.

We seem to be circling around the same question: is the proper model for a war of seccession an all or nothing civil war on the model of the English and Russian civil wars? Or is it more like a colonial conflict such as the AWI or the various liberation wars in Latin America? Presumably the best model would be more like the Catalan or Portuguese wars of seccession, but I don't really know much about them.

"Lee caused more confederate casualties than Union casualties"

Not even close to being true. The only Lee battles where Confederate casualties were more than the Union were:
Cheat Mountain (his first battle, less than 100 more);
South Mountain (about 300 more);
Gettysburg (up to 5,000 more, estimates vary); and his last
Appomattox Court (about 400 more and the ANV surrendered).

His first battle of Commander ANV was Battle of the Seven Days where the Union lost 4,500 more. At Fredericksburg the Union lost more than 7,000 more. So, those two alone double the totals lost in the combined four listed above.

Longstreet was a fine commander. Lee was better and was greatly admired by his men.

"His whole make-up of form and person, looks and manner had a kind and soothing magnetism about it that drew everyone to him and made them love, respect and honor him. I fell in love with the old gentleman and felt like going home with him'."
Samuel R. Watkins – Co. Aytch.

And North Vietnam never should have been able to beat the United States of America, except…..

Kim

Longstreet was a capable corps commander but not suited for independent army command, as demonstrated by his unsuccessful Knoxville Campaign in the fall of 1863. His confidence took a hit, and he reacted to the campaign's failure by blaming others, much as he had after the Battle of Seven Pines in the previous year's Peninsula Campaign. The list of good army commanders in the Confederate Army is a short one, Robert E. Lee.

Kim, there was a legend back in The Day that about 1968 Robert MacNamara and his "Whiz Kids" fed into a computer forces, resources, losses and such into a computer and asked it to calculate when the United States would win the Vietnam War. The computer said we'd already won it in 1966.

Getting back to the ACW, what has long intrigued me is that even the officers Lee effectively booted out of the ANV--some of them all the way to the Trans-Mississippi--almost without exception continued to respect and sometimes to love him. I think D.H. Hill might count as an exception, but there weren't many. High commanders often have great charisma, but the effect usually wears off with death and defeat. Not with Lee. There was something about the man beyond that.

Not even close to being true. The only Lee battles where Confederate casualties were more than the Union were:
Cheat Mountain (his first battle, less than 100 more);
South Mountain (about 300 more);
Gettysburg (up to 5,000 more, estimates vary); and his last
Appomattox Court (about 400 more and the ANV surrendered).

Robert E. Lee was by far the bloodiest general in terms of casualties incurred, of the entire war. In his command of the Army of the Tennessee Grant suffered 40,000 casualties. During the same time period Lee had 75,000 to 80,000 casualties.

It's estimated that approximately 55-60% of Lee's army became casualties (killed, wounded, or missing) at some point during the war.

Officers under Lee stood a 1 in 2 chance of becoming a casualty during the war. Grant didn't start taking the huge casualties he is known for until he faced Lee.

"Scapegoat in Victory: James Longstreet and the Memory of Second Bull Run" with Dr. Gary Gallagher

YouTube link

Robert E. Lee was by far the bloodiest general in terms of casualties incurred, of the entire war. In his command of the Army of the Tennessee Grant suffered 40,000 casualties. During the same time period Lee had 75,000 to 80,000 casualties.

It is difficult to compare two different time periods, two different theatres and two different armies that both varied in size over time.

It's estimated that approximately 55-60% of Lee's army became casualties (killed, wounded, or missing) at some point during the war.

Where is that estimation? 55-60% of what total manpower for the ANV? It doesn't add up for me.
At Gettysburg the ANV suffered just under 39.14% of its strength in total casualties and it was the highest by far. Lee's next highest casualty percentage was at Sharpsburg/Antietam (27.15%).

Officers under Lee stood a 1 in 2 chance of becoming a casualty during the war.

No, that 55-60% figure seems false.

Grant didn't start taking the huge casualties he is known for until he faced Lee.

Well, yes. Different theatres and different numbers involved.
Still, there is The Crater where Union casualties were 44.68%. Fortunately, the numbers involved for that action were comparatively small so total casualties were only 3,798. Burnside [I think rightly] got the blame but Grant was in charge and the buck stopped with him.

"He seemed to have a right idea at Gettysburg…"

Which, I might point out, he didn't mention to anyone until Lee was dead. His only two independent commands were miserable failures.

"He seemed to have a right idea at Gettysburg…"

Which, I might point out, he didn't mention to anyone until Lee was dead.

He mentioned it well before then.
From the Official Records – babel.hathitrust.org/cgi/pt?id=coo.31924077728255&seq=362&q1=.
"The order for this attack [Pickett's Charge], which I could not favor under better auspices, would have been revoked had I felt that I had that privilege."

Robert – Your comment on McNamara and the Whiz Kids was hilarious! Also, funny you mentioned DH Hill. One of my favorite commanders who I always felt deserved a chance at Corp command in the ANV after Jackson's death.

His falling out with Lee began with his criticism of the attack at Malvern Hill. DH Hill, like George Patton didn't "know when to keep his mouth shut!"

Contemptible – Yes, the ANV took a lot of casualties. But consider that in a one-year period from the summer of 1862 to summer of 1863, Lee fought six separate campaigns that all led to major battles:

The Seven Days, 2nd Bull Run, Antietam, Fredericksburg, Chancellorsville and Gettysburg.

His army was always outnumbered in these battles, yet he would win 4 of the 6 but only suffered more casualties than the Union twice in those actions. The percentage of casualties for a smaller army will almost always be higher.

A better comparison would be Livermore's method of comparing your casualties as a ratio of your opponent's strength rather than your own.

Kim

Grant fought in some battles and campaigns himself as commander of the Army of the Tenn.

Battle of Shiloh
Siege of Corinth
Battle of Iuka
Battle of Corinth
Vicksburg Campaign (including his Jackson MS campaign)
Chattanooga Campaign

As a percentage of his command Lee accumulated far more casualties during the entire war. This is accepted by most Historians including McPherson and Gallagher. It's just a fact. He was extremely aggressive and as some say, bleed the Confederacy dry.

For the Overland Campaign:

Union Forces: Grant/Meade
Total Casualties: Approximately 55,000 out of 118,700 engaged.
Percentage: Roughly 46%.

Confederate Forces: Lee
Total Casualties: Approximately 32,600 out of 64,000 engaged.
Percentage: Around 51%.

You can consult the Official Records, "Battle Cry of Freedom" by James M. McPherson, any number of Grant biographies.

As far as Livermore's method, its a good starting point but I prefer Dupy.

I'm unsure where you get your figures from. At Shiloh the AotT had less than 50,000 men. During the Vicksburg Campaign it still had way below 100,000.
The ANV also varied over time. In the Seven Days it was just over 90,000; a year later at Gettysburg it was about 75,000; another year later at the start of the Richmond/Petersburg Campaign it was up over 80,000 again.

It's nonsensical to pick a figure from one point in time and then add up all the casualties over the entire four years and say the casualty rate is X%.
That's why I said earlier "It is difficult to compare two different time periods, two different theatres and two different armies that both varied in size over time." In fact, it's almost impossible as the different theatres include factors that can't be properly compared. One example would be the differences in weapons. The soldiers in the east generally had the better (i.e. deadlier) weapons and a lot more (and better) artillery.

Don't you just love this phrase concerning Gen. Longstreet!
----"He seemed to have a right idea at Gettysburg…"----

As wargamers we all 'know' it, 'hear' it, but….
Where is this at, I would love to see this presentation, the maps showing the routes, the positions, the supports, logistic support positions, well you know like it is real thing.

Links? Thanks

Don't you just love this phrase concerning Gen. Longstreet!
----"He seemed to have a right idea at Gettysburg…"----

As wargamers we all 'know' it, 'hear' it, but….
Where is this at, I would love to see this presentation, the maps showing the routes, the positions, the supports, logistic support positions, well you know like it is real thing.

Links? Thanks

The best primary source is probably the one I provided earlier from the Official Records, babel.hathitrust.org/cgi/pt?id=coo.31924077728255&seq=362&q1= ("The order for this attack [Pickett's Charge], which I could not favor under better auspices, would have been revoked had I felt that I had that privilege."). For Longstreet, or others, to say much more at the time would have been problematic.
Longstreet goes into more detail in his memoirs From Manassas to Appomattox.

As I posted here on another forum I believe that, apart from Lee (the decision was his) the main fault for the failure of Pickett's Charge was Pendleton's. Pendleton was out-generaled by Hunt. Hunt deceived the CSA with silenced guns and then made them pay a heavy price with his clever positioning of guns when they started firing again.
The CSA needed a few more men in the assault too. As it was, they got close. Another 5-6,000 men could have made all the difference.

Quaama,

Nice reply, good stuff, thanks.
True, Longstreet had issues with the July 3rd Attack. Yet he was not on his best day also. Gen. Lee would say the attack was not supported as expected, hanging chad there to think on.

The role of Gen. Hunt, right on, the real story for the Union, his best day during the war. Old man Pendleton was out of his element, key is he moved the limbered guns that were to move forward to support the attack to the rear for safety then when the attack is launched, where are they?? Not engaged. Think as a wargamer if those guns were on the wings of the Brigades, no union units could wheel and flank the attacking lines.

Still we have that wargamer mystery of that wild move to the South on July 2nd that could have worked. Just dream.
Thanks for sharing.

Yeah, Lee never amplified that "not supported"--neither who was supposed to have been supporting with what, and who (other than the army commander, of course) was responsible for that lack of support. Lee's admirers have a laundry list of candidates for the non-supporter, and it's cynical of me to think he might have intended that. Lee was in some ways a great man, but I don't think any of us own up to all our faults.

To me, Pickett's charge shows someone's hand other than Longstreet's, and Lee is about the only candidate. If you look at Longstreet's work in the attack--Second Bull Run, the Second Day at Gettysburg, Chickamauga and the Wilderness--they're carefully lined up and formations tend to get steadily deeper. I can't imagine Old Pete sending in brigades without supports the way some of them were on the Third Day if he'd had a free hand in conducting the attack.

Quaama-I would love to know your source for the ANV having over 80,000 men at the start of the "Richmond/Petersburg Campaign" and how that number was calculated. Lee started the Overland Campaign with 8 infantry divisions in the ANV, none of which were as strong as the Light Division had been a year earlier. Are they including troops with Breckinridge in the Shenandoah Valley and troops with Beauregard (many of whom actually arrived as the campaign was under way) south of the James? Elements of both of those forces joined Lee for Cold Harbor, but then again elements of the Army of the James plus a string of reinforcements joined Grant and Meade during the same period.

Quaama-I would love to know your source for the ANV having over 80,000 men at the start of the "Richmond/Petersburg Campaign" and how that number was calculated.

As I was only trying to show that this numbers widely fluctuated over time I believe I got it from Wikipedia. The number would certainly include the ANV force in the Valley and appears to also include Beauregard's force.
It would have been helpful to have this book (The Army of Northern Virginia: Organization, Strength, Casualties, 1861-1865 but sadly I do not.
It would be a mammoth task to try and arrive at an accurate percentage figure for casualties over an extended period of time due to the changing strength of an army. The best you can do is tally up the casualties for each battle based upon the total army size at the time and then average it overall. I haven't done that but for Lee his maximum percentage loss must be below 39.14% (his biggest loss, Gettysburg) and Grant's must be below 44.68% (his biggest loss, The Crater). I suspect the average for both commanders would be significantly below those extreme percentages.

Although such high percentages are difficult to comprehend in contemporary warfare, they can be attributed to significant improvements in weaponery and a failure of tactics to quickly adapt to those new weapons. A mistake repaeated on a grander scale in WWI. A situation that didn't change much until Sir John Monash began to introduce 'peaceful penetration' in 1918.