The sources for troop numbers in the Maryland Campaign

If the numbers for the AoNV were substantially higher, how and when were the number of casualties for Antietam reported? There was apparently no reliable systematic recording of numbers as even Lee was unsure of the numbers of men present on the battlefield. Interestingly in McClellan's report (in the O.R.) he stated 'about 2,700 of the enemy's dead were counted and buried upon the battlefield of Antietam' and more tellingly said 'a portion of their dead had been previously buried by the enemy'. This suggests the Confederates buried those dead that were within their own lines the day after the battle. The line was by then considerably shortened and I will need to get some idea as to approximately how many dead there could have been on this part of the field. Even if this number is relatively small, circa 300, this already gives a total of 3,000 dead. This is double the recorded 1,550 dead. What I find interesting is if you double the numbers present would that mean double the casualties considering the ferocity of the battle that everyone who was there agrees on?
Now I know some will say it was in McClellan's interest to inflate the number of Confederate casualties, however nobody disputed these numbers at the time they were recorded so that would suggest them to be reasonable and reliable. Similarly was it just as plausible for it to be in Lee's best interests to downplay the horrific losses suffered?
This to me is important for several reasons. If the number of total casualties is increased then America's bloodiest day is even bloodier! The total number of casualties (for both sides) now probably exceeds Shiloh and Chancellorsville, and Antietam becomes the fourth bloodiest battle of the war, only exceeded by battles that took place over three days. The impact of these losses becomes almost impossible to account for. Today we know about Post Traumatic Stress Disorder and other psychological problems caused by people who observe or are involved in horrific events so to continue to underplay the carnage that Antietam ultimately was is to undervalue the part played by all those involved and the impact it had upon them.
 
The line was by then considerably shortened and I will need to get some idea as to approximately how many dead there could have been on this part of the field. Even if this number is relatively small, circa 300, this already gives a total of 3,000 dead.
The best way to count is by counting actual bodies buried in cemetries as Confederate bodies and calling it a lowball value. As I understand it the field burials were later reburied, but any Confederates wearing looted Union uniforms may not have been correctly classified as such by the burial detail.

Now I know some will say it was in McClellan's interest to inflate the number of Confederate casualties, however nobody disputed these numbers at the time they were recorded so that would suggest them to be reasonable and reliable. Similarly was it just as plausible for it to be in Lee's best interests to downplay the horrific losses suffered?
The captured number is fairly solid because it's made up of captured wounded under care by the army medical director, plus captured unwounded subsequently exchanged (for which exchange paperwork exists). The killed number is fairly solid because, you know, corpses.

The wounded number is unclear, and for those purposes I've used the reported Confederate wounded (which would consist of actual wounded men in the Confederate hospital systems).

Any other casualties on top of this would consist of:

Wounded men who were not collected up by the Confederate hospital system and died on the Confederate side of the river, but were not recorded as "wounded" in the documents.
Captured men who were not exchanged, and for whom no exchange paperwork thus exists.
Dead men whose bodies were either not found or who were not identified as Confederate when found.

I think all of these categories have at least some men in them.

I think any disparities in Confederate reporting is simply because Lee's army was pretty disorganized - in both the organizational and paperwork sense. Lee may have had no more than a vague idea of how many men he had with him in the first place, while some regiments were so hard hit they had almost no senior officers left; it's easy to see how trying to count up the men killed or MIA might go a bit less than smoothly in that situation, while at least for the wounded you actually have them with you.

What I find interesting is if you double the numbers present would that mean double the casualties considering the ferocity of the battle that everyone who was there agrees on?
Using the Union 1st Corps as a baseline (63% of theoretical PFD were in line of battle) and assuming 70% is the norm, one can reasonably assume that of the ~175,000 pre-straggle PFD at Antietam about ~122,000 were in some sense in line of battle and available to be engaged on the 17th (this number includes Sykes, Morell and 6th Corps). Of this number more than 25,000 became casualties on that day. (Maryland campaign overall casualties, ignoring the surrender of Harpers Ferry, are on the order of 32,000 but it's likely a lot of those were either on the 14th or swept up on the 17th).
Very roughly that's about one in five, or perhaps two in nine.

This isn't quite as nasty as the most vicious battles of the Napoleonic Wars (Waterloo saw about one in four and is also a one-day battle) but it's up there.
 
The best way to count is by counting actual bodies buried in cemetries as Confederate bodies and calling it a lowball value. As I understand it the field burials were later reburied, but any Confederates wearing looted Union uniforms may not have been correctly classified as such by the burial detail.


The captured number is fairly solid because it's made up of captured wounded under care by the army medical director, plus captured unwounded subsequently exchanged (for which exchange paperwork exists). The killed number is fairly solid because, you know, corpses.

The wounded number is unclear, and for those purposes I've used the reported Confederate wounded (which would consist of actual wounded men in the Confederate hospital systems).

Any other casualties on top of this would consist of:

Wounded men who were not collected up by the Confederate hospital system and died on the Confederate side of the river, but were not recorded as "wounded" in the documents.
Captured men who were not exchanged, and for whom no exchange paperwork thus exists.
Dead men whose bodies were either not found or who were not identified as Confederate when found.

I think all of these categories have at least some men in them.

I think any disparities in Confederate reporting is simply because Lee's army was pretty disorganized - in both the organizational and paperwork sense. Lee may have had no more than a vague idea of how many men he had with him in the first place, while some regiments were so hard hit they had almost no senior officers left; it's easy to see how trying to count up the men killed or MIA might go a bit less than smoothly in that situation, while at least for the wounded you actually have them with you.


Using the Union 1st Corps as a baseline (63% of theoretical PFD were in line of battle) and assuming 70% is the norm, one can reasonably assume that of the ~175,000 pre-straggle PFD at Antietam about ~122,000 were in some sense in line of battle and available to be engaged on the 17th (this number includes Sykes, Morell and 6th Corps). Of this number more than 25,000 became casualties on that day. (Maryland campaign overall casualties, ignoring the surrender of Harpers Ferry, are on the order of 32,000 but it's likely a lot of those were either on the 14th or swept up on the 17th).
Very roughly that's about one in five, or perhaps two in nine.

This isn't quite as nasty as the most vicious battles of the Napoleonic Wars (Waterloo saw about one in four and is also a one-day battle) but it's up there.

I' m certain that I'm missing it in this thread but what is your estimate for the number of fighting men that Lee put into action on September 17?

Ryan
 
I' m certain that I'm missing it in this thread but what is your estimate for the number of fighting men that Lee put into action on September 17?
This is a very difficult topic because different numbers of men straggled by different amounts.

If we assume that the Union forces and the Confederate forces straggled by about the same amount (i.e. 63% of theoretical PFD gets into line of battle, as per the Union 1st Corps), then the rough estimate is about 47,000 as against 55,000 Union troops on the field (i.e. including Morell and Franklin, but not Humphreys and Couch). In both cases this is just 73,000 (CS) and 87,000 (US) times 0.63.


Going into more detail means looking at individual divisions, brigades or even regiments, and that means trying to source the numbers where they claimed how many troops they had. This is particularly problematic when the numbers we have conflict with one another - for example Jackson's division is down in Carman as 1,784 infantry, but then Starke's brigade (1/3 of the division) claimed about 1,400-1,500 infantry at Antietam. This seems to be because Jackson's divisional strength was measured when they'd just arrived and all the stragglers been collected up, but Starke's brigade was measured when they were about to go into action (which is much closer to what the 63% number for 1st Corps represents).

On the 2nd September returns, per Hartwig, Jackson's division was (in PFD):


JR JonesGrigsby
1160​
Johnson
812​
Warren
1543​
Starke
1623​
Arty
440​
6 Btys

So 1,400 for Starke would indicate that his brigade was at 86% of nominal strength, while 1,784 infantry for the whole division would indicate that the division was at about 35% of nominal strength. This difference is pretty huge - if applied across the whole army it would mean the difference between claiming about 63,000 and claiming about 25,500.

67th Tigers went through the numbers in Carman and reassessed them a few years ago, including going to Carman's sources, and the rough numbers he gets are:

DH Hill: DH Hill claimed 3,000 infantry, but Carman calculated 5,449 infantry and 346 artillery.
Via Clemens we get:
Ripley's brigade: 1,349 infantry into action
Rodes' brigade: 3rd, 6th and 12th Alabama carried 840 into action, excluding at least the officers of the 12th. 5th Alabama was a small regiment, but no clue about the 26th; if the 5th and 26th average the same as the other three then it's ca. 1,400.
Colquitt's brigade, from Carman's correspondence:
6th Georgia: 300+ (and one company on picket not counted)
23rd Georgia: 485 men (not officers)
27th Georgia: 400 men (not officers)
28th Georgia: 250 men or 250-275 officers and men
13th Alabama: Carman guessed 310 based on a 2nd September strength of 612
Which implies that there were ~1,780 men plus officers, for a brigade strength of ~1,900
Garland's brigade:
Carman gives the brigade 756, but it was the strongest in the division on the 2nd September (though it did then take plenty of casualties at South Mountain) and the 5th North Carolina had ~625 men at Antietam. Adding officers and assuming the other four regiments are each about half the size of the 5th NC gives an estimate of about 2,100, but I'd say we could go with 1,700 to avoid overclaiming. Effectively this is assuming the other four regiments average 250 officers and men.

GB Anderson's brigade - Carman gives 1,174 and this seems fairly solid.
Divisional total:
1349+1400+1900+1700+1174 = 7,523 infantry, and 346 gunners.


McLaws: Carman gives 2,823 infantry and 138 gunners. This might actually make sense, on 2nd September McLaws disposed of 7,340 infantry and 419 gunners but they got hit hard at Crampton's Gap and suffered 1,907 claimed infantry casualties. If the actual casualties were higher and there was the usual straggling, or those casualties and a bit more than the usual straggling, then I suppose it's possible they could be down to about 3,000.

RH Anderson: The brigades except for Armistead (who remained in reserve) were sent to reinforce DH Hill, who estimated it at ca. 3,000-4,000. As we've seen DH Hill's estimated strength was really low for his own division, so it could be considerably higher. (The 22nd September return gives 5,324 PFD, and it suffered 1,278 casualties at Antietam; it'd probably be reasonable to say it had about 5,000 actually with the division once Armistead is counted.)

Walker: Carman calculated 3,764 infantry and 230 artillery.

DR Jones: DR Jones himself estimated "only 2,430 men" from a pre-campaign PFD of 8,953 infantry; he suffered about 1,000 casualties in the pre-Antietam fighting, but being down to less than 2,500 simply isn't credible. In particular this division includes Drayton's brigade, which is the one that had had almost no straggling until September 11th, so a lot of the hypothetical stragglers would have had to fall out of line and be swept up.
Carman estimated 3,311 infantry and 81 artillery, but going brigade by brigade:

Toombs: Toombs claimed over 400 muskets in the 2nd and 20th Georgia, while Carman estimated 357 officers and men in the same two regiments. Then 15th and 17th Georgia (Carman est. 281 muskets) joined them, and half the 11th Georgia (reported as 140 muskets in the five companies present).
This implies about 750-780 men minus officers, or a bit more with officers (so ca. 825).

Garnett: Carman gave 261 officers and men in the brigade, arguing that the brigade was recruited from near where Lee crossed the Potomac and briefly deserted. This would imply something like 80% of the brigade had either done that or was elsewhere.

Kemper: Carman estimates 443 on the field by adding regimental reports and guessing for the 28th VA, but others reported the brigade at 500-600 muskets (which would imply 600 or so with officers added, indicating the 28th VA was a strong regiment). 600 would also indicate straggling of about 50%.

GT Anderson - Carman estimates 597, but see Hood/Evans...

Drayton: Carman estimates 465, excluding 11th Georgia (detached and one wing fought in Toombs' brigade, 140 men counted there). Carman was told by a veteran the 15th SC had 300 men, but he used 200 in his calculation. Carman's estimate of 100 for the 51st Georgia is given no basis but we'll use it. The Phillips Legion infantry was also present, but Carman doesn't include it.
Correcting the 15th SC from 200 to 300, and adding the Phillip's Legion (ca. 135) plus adding officers would be ca. 700 men plus about 80 officers, so 780.

Jenkins: Carman quotes a newspaper to give 755 but in correspondence with the brigadier he's told 1,250 officers and men plus the 1st SC (106). So 1,356.

This totals to 825+261+600+780+1356 infantry, for 3,822 infantry (not including GT Anderson) plus 81 artillery.

Hood/Evans:

Carman says Evans' brigade straggled really badly, down to 284 infantry and 112 gunners for 396 all told. That's down from 1,058 on 2nd September, though there were 216 casualties so it means "only" about 53% straggling, or 47% of the strength in line.

Hood's brigade and Whiting's brigade are estimated at 2000 infantry (Hood gave this) and 304 artillery, and this does not include officers (so ca. 230 officers). 2230 infantry means about 62% of theoretical strength in line.

GT Anderson's brigade: 597, and Evans claimed it in his report. That's about 43% of theoretical strength which is another bad straggle.

Total for these four brigades considered here is 3,111 infantry and 416 artillery.

Jackson: As covered above, the number Carman gives is 1,784 infantry and 310 artillery, but this is just after the arrival on the field. If we take Starke's number of 1,400-1,500, take the low number (1,400) and correct the other three brigades to match then we multiply their September 2 strength by 0.86, to give:
Grigsby 1,000
Johnson 700
Warren 1,330
Starke 1,400
Total 4,430 infantry and 310 artillery

Ewell:
Carman gives 3,904 infantry and 223 artillery, but for once there's full reports in the OR. Ewell moved more slowly than the Stonewall division and took care to keep his straggling under control (he paused south of Boteler's Ford to collect up stragglers before crossing), and Lawton and Early's brigades match very closely to 22nd September PFD plus casualties; the other two don't.
It looks like there's an artillery battery buried in the reports for Hays and Trimble (as Ewell's division reported artillery in brigade totals) and the numbers for Hay and Trimble are also a bit vague - Hays' entire brigade is reported as the force Hays took to the wheatfield, and Trimble is just "out of less than 700 men carried into action". Assuming the four brigades behaved similarly you get about 1,000 in both (1078 instead of 550 for Hays and 1029 instead of 700 for Walker) but this includes the artillery. This would give a total of about 4,400 infantry and 223 artillery, and would mean that there were 73% of the infantry in battle - what we'd expect from a division that controlled straggling especially well.

AP Hill: Carman gives 2,231 infantry for the three engaged brigades, plus 337 artillery. The three engaged brigades were Branch, Archer and Gregg (2nd September total 3,887, so 57.3% of 2nd September strength engaged), with Pender and Field (2nd September total 2,932) not engaged; if Pender and Field straggled as much as Branch, Archer and Gregg, that gives an extra 1,683 infantry for a total of 3,914 infantry and 337 artillery on the field.

Total strengths of the infantry divisions:

DH Hill 7523 + 346
McLaws 2823 + 138
Anderson 5,000 + 0
Walker 3,764 + 230
DR Jones 3,822 + 81
Hood/Evans 3,311 + 416
Jackson/Stonewall 4,430 + 310
Ewell 4,400 + 223
AP Hill 3,914 + 337

Total infantry 38,987

Carman gives the cavalry directly at 4,500, and the total artillery at 3,629. This would mean a grand total of

47,116 effectives




This estimate has large error bars on it, and could be off by a few thousand either way. There were also quite a lot of men who have to have been just behind the lines, as taking the September 22 return and adding back casualties gives just under 60,000 for the whole army - a difference of 13,000 men.
 
This is a very difficult topic because different numbers of men straggled by different amounts.

If we assume that the Union forces and the Confederate forces straggled by about the same amount (i.e. 63% of theoretical PFD gets into line of battle, as per the Union 1st Corps), then the rough estimate is about 47,000 as against 55,000 Union troops on the field (i.e. including Morell and Franklin, but not Humphreys and Couch). In both cases this is just 73,000 (CS) and 87,000 (US) times 0.63.


Going into more detail means looking at individual divisions, brigades or even regiments, and that means trying to source the numbers where they claimed how many troops they had. This is particularly problematic when the numbers we have conflict with one another - for example Jackson's division is down in Carman as 1,784 infantry, but then Starke's brigade (1/3 of the division) claimed about 1,400-1,500 infantry at Antietam. This seems to be because Jackson's divisional strength was measured when they'd just arrived and all the stragglers been collected up, but Starke's brigade was measured when they were about to go into action (which is much closer to what the 63% number for 1st Corps represents).

On the 2nd September returns, per Hartwig, Jackson's division was (in PFD):


JR JonesGrigsby
1160​
Johnson
812​
Warren
1543​
Starke
1623​
Arty
440​
6 Btys

So 1,400 for Starke would indicate that his brigade was at 86% of nominal strength, while 1,784 infantry for the whole division would indicate that the division was at about 35% of nominal strength. This difference is pretty huge - if applied across the whole army it would mean the difference between claiming about 63,000 and claiming about 25,500.

67th Tigers went through the numbers in Carman and reassessed them a few years ago, including going to Carman's sources, and the rough numbers he gets are:

DH Hill: DH Hill claimed 3,000 infantry, but Carman calculated 5,449 infantry and 346 artillery.
Via Clemens we get:
Ripley's brigade: 1,349 infantry into action
Rodes' brigade: 3rd, 6th and 12th Alabama carried 840 into action, excluding at least the officers of the 12th. 5th Alabama was a small regiment, but no clue about the 26th; if the 5th and 26th average the same as the other three then it's ca. 1,400.
Colquitt's brigade, from Carman's correspondence:
6th Georgia: 300+ (and one company on picket not counted)
23rd Georgia: 485 men (not officers)
27th Georgia: 400 men (not officers)
28th Georgia: 250 men or 250-275 officers and men
13th Alabama: Carman guessed 310 based on a 2nd September strength of 612
Which implies that there were ~1,780 men plus officers, for a brigade strength of ~1,900
Garland's brigade:
Carman gives the brigade 756, but it was the strongest in the division on the 2nd September (though it did then take plenty of casualties at South Mountain) and the 5th North Carolina had ~625 men at Antietam. Adding officers and assuming the other four regiments are each about half the size of the 5th NC gives an estimate of about 2,100, but I'd say we could go with 1,700 to avoid overclaiming. Effectively this is assuming the other four regiments average 250 officers and men.

GB Anderson's brigade - Carman gives 1,174 and this seems fairly solid.
Divisional total:
1349+1400+1900+1700+1174 = 7,523 infantry, and 346 gunners.


McLaws: Carman gives 2,823 infantry and 138 gunners. This might actually make sense, on 2nd September McLaws disposed of 7,340 infantry and 419 gunners but they got hit hard at Crampton's Gap and suffered 1,907 claimed infantry casualties. If the actual casualties were higher and there was the usual straggling, or those casualties and a bit more than the usual straggling, then I suppose it's possible they could be down to about 3,000.

RH Anderson: The brigades except for Armistead (who remained in reserve) were sent to reinforce DH Hill, who estimated it at ca. 3,000-4,000. As we've seen DH Hill's estimated strength was really low for his own division, so it could be considerably higher. (The 22nd September return gives 5,324 PFD, and it suffered 1,278 casualties at Antietam; it'd probably be reasonable to say it had about 5,000 actually with the division once Armistead is counted.)

Walker: Carman calculated 3,764 infantry and 230 artillery.

DR Jones: DR Jones himself estimated "only 2,430 men" from a pre-campaign PFD of 8,953 infantry; he suffered about 1,000 casualties in the pre-Antietam fighting, but being down to less than 2,500 simply isn't credible. In particular this division includes Drayton's brigade, which is the one that had had almost no straggling until September 11th, so a lot of the hypothetical stragglers would have had to fall out of line and be swept up.
Carman estimated 3,311 infantry and 81 artillery, but going brigade by brigade:

Toombs: Toombs claimed over 400 muskets in the 2nd and 20th Georgia, while Carman estimated 357 officers and men in the same two regiments. Then 15th and 17th Georgia (Carman est. 281 muskets) joined them, and half the 11th Georgia (reported as 140 muskets in the five companies present).
This implies about 750-780 men minus officers, or a bit more with officers (so ca. 825).

Garnett: Carman gave 261 officers and men in the brigade, arguing that the brigade was recruited from near where Lee crossed the Potomac and briefly deserted. This would imply something like 80% of the brigade had either done that or was elsewhere.

Kemper: Carman estimates 443 on the field by adding regimental reports and guessing for the 28th VA, but others reported the brigade at 500-600 muskets (which would imply 600 or so with officers added, indicating the 28th VA was a strong regiment). 600 would also indicate straggling of about 50%.

GT Anderson - Carman estimates 597, but see Hood/Evans...

Drayton: Carman estimates 465, excluding 11th Georgia (detached and one wing fought in Toombs' brigade, 140 men counted there). Carman was told by a veteran the 15th SC had 300 men, but he used 200 in his calculation. Carman's estimate of 100 for the 51st Georgia is given no basis but we'll use it. The Phillips Legion infantry was also present, but Carman doesn't include it.
Correcting the 15th SC from 200 to 300, and adding the Phillip's Legion (ca. 135) plus adding officers would be ca. 700 men plus about 80 officers, so 780.

Jenkins: Carman quotes a newspaper to give 755 but in correspondence with the brigadier he's told 1,250 officers and men plus the 1st SC (106). So 1,356.

This totals to 825+261+600+780+1356 infantry, for 3,822 infantry (not including GT Anderson) plus 81 artillery.

Hood/Evans:

Carman says Evans' brigade straggled really badly, down to 284 infantry and 112 gunners for 396 all told. That's down from 1,058 on 2nd September, though there were 216 casualties so it means "only" about 53% straggling, or 47% of the strength in line.

Hood's brigade and Whiting's brigade are estimated at 2000 infantry (Hood gave this) and 304 artillery, and this does not include officers (so ca. 230 officers). 2230 infantry means about 62% of theoretical strength in line.

GT Anderson's brigade: 597, and Evans claimed it in his report. That's about 43% of theoretical strength which is another bad straggle.

Total for these four brigades considered here is 3,111 infantry and 416 artillery.

Jackson: As covered above, the number Carman gives is 1,784 infantry and 310 artillery, but this is just after the arrival on the field. If we take Starke's number of 1,400-1,500, take the low number (1,400) and correct the other three brigades to match then we multiply their September 2 strength by 0.86, to give:
Grigsby 1,000
Johnson 700
Warren 1,330
Starke 1,400
Total 4,430 infantry and 310 artillery

Ewell:
Carman gives 3,904 infantry and 223 artillery, but for once there's full reports in the OR. Ewell moved more slowly than the Stonewall division and took care to keep his straggling under control (he paused south of Boteler's Ford to collect up stragglers before crossing), and Lawton and Early's brigades match very closely to 22nd September PFD plus casualties; the other two don't.
It looks like there's an artillery battery buried in the reports for Hays and Trimble (as Ewell's division reported artillery in brigade totals) and the numbers for Hay and Trimble are also a bit vague - Hays' entire brigade is reported as the force Hays took to the wheatfield, and Trimble is just "out of less than 700 men carried into action". Assuming the four brigades behaved similarly you get about 1,000 in both (1078 instead of 550 for Hays and 1029 instead of 700 for Walker) but this includes the artillery. This would give a total of about 4,400 infantry and 223 artillery, and would mean that there were 73% of the infantry in battle - what we'd expect from a division that controlled straggling especially well.

AP Hill: Carman gives 2,231 infantry for the three engaged brigades, plus 337 artillery. The three engaged brigades were Branch, Archer and Gregg (2nd September total 3,887, so 57.3% of 2nd September strength engaged), with Pender and Field (2nd September total 2,932) not engaged; if Pender and Field straggled as much as Branch, Archer and Gregg, that gives an extra 1,683 infantry for a total of 3,914 infantry and 337 artillery on the field.

Total strengths of the infantry divisions:

DH Hill 7523 + 346
McLaws 2823 + 138
Anderson 5,000 + 0
Walker 3,764 + 230
DR Jones 3,822 + 81
Hood/Evans 3,311 + 416
Jackson/Stonewall 4,430 + 310
Ewell 4,400 + 223
AP Hill 3,914 + 337

Total infantry 38,987

Carman gives the cavalry directly at 4,500, and the total artillery at 3,629. This would mean a grand total of

47,116 effectives




This estimate has large error bars on it, and could be off by a few thousand either way. There were also quite a lot of men who have to have been just behind the lines, as taking the September 22 return and adding back casualties gives just under 60,000 for the whole army - a difference of 13,000 men.

Thank you for the information. That's about what I had figured as well.

Ryan
 
Eyewitness reports on parts of Lee's army
I wanted to correct this post with additional information I was not previously aware of. That is that the force which Steiner saw marching through Frederick on the 11th (DH Hill's division) was only four out of the five brigades actually in DH Hill's force.

What this means is that Steiner's estimates were:

"Not more than 64,000" - Lee's main body.
"8,000" - four of DH Hill's five brigades (the missing one was GB Anderson).




Stuart's cavalry in the post-battle numbers was 5,761 and all the cavalry in Allen's thesis is 4,155 with Stuart and 1,509 in Hampton's reinforcements (for 5,664).
Walker's division is 3,994 PFD in the post-battle numbers from October 10 (and 3,207 on September 22) and reported over 1,000 casualties in the Maryland Campaign, so can be reasonably estimated at ca. 5,000. It was 5,159 PFD in Allen's thesis.
GB Anderson is harder to determine, but represented four out of the 23 regimental organizations in DH Hill's division; in Hartwig, GB Anderson's infantry is 1,427 out of the 9,842 strength of DH Hill's division (including artillery). I would say that 1,400-1,500 was a reasonable estimate, or possibly higher if there was a battery with them.



This means that taking Steiner's estimates and comparing them to what we would expect him to see:

We would expect to see
~75,000 (total Confederate PFD)
-10,500 (Walker and Stuart PDF)
-~1,500 (GB Anderson)

= 63,000 (September 10 and 11 combined) (of which about 8,300-8,400 would be expected to be seen on the 11th)

He saw:
"Not more than 64,000" (September 10)
And "8,000" (September 11)


To me this seems to imply that the September 10th numbers include some amount of non-PFD troops, while the September 11 numbers are pretty close to PFD. It also implies little to no straggling, in that the amount of straggling we could point to for DH Hill's division is only 5% and within the margin of error of the "8,000" estimate (though straggling may be as much as 10% if Steiner actually saw ~7,500 and should have seen ~8,400.)
 
So here's something I think is interesting, which is an example of how an author with a speciality can be misled by mistakenly believing the assertions of someone outside their field.


Hennessy has made a deep study of Second Bull Run, and consequently has his own idea of how strong the Confederate army was there. However, in his epilogue he says:


On August 15 Lee had counted probably fifty-five thousand men in his army. On September 3, despite the addition of three new divisions totaling about nine thousand men, the number was only about fifty thousand.

Hennessy, John J.. Return to Bull Run . University of Oklahoma Press. Kindle Edition.

He then gives 40,000 at Antietam.

The footnote for this passage says:

For numbers at Antietam see Sears, Landscape Turned Red, p. 69; Murfin, Gleam of Bayonets, p. 198. O.R. XIX, Pt. 2, pp. 590–591.

(The OR cite has no information on Lee's strength.)

The thing which is interesting about this is that the "three new divisions" are presumably DH Hill, McLaws and Walker.
DH Hill's division had 23 regiments in 5 brigades; McLaws had 15 regiments and 1 legion in 4 brigades; Walker had 9 regiments in 2 brigades. Thus the total is 11 brigades and 48 regiments. (For these purposes I'm ignoring the cavalry under Hampton which joined the Confederate army along with DH Hill.)

The casualties claimed by these units in the Maryland campaign are:
DH Hill 3,241
McLaws 2,081
Walker 1,103
For a total of 6,425.

And on the 22nd of September, in the very first (disrupted) post-battle return, they are:
Walker's division 221 officers and 3207 enlisted
McLaws' division 269 men and 3659 enlisted
DH Hill's division 332 men and 4739 enlisted
Total 12427

So the reinforcement column cannot have been less than about 19,000 men just in those three named divisions, and (given how those divisions swell further by October 10 to a strength of 18,510 by October 10) more likely the column's total strength inclusive of cavalry was about 25,000 men by Confederate PFD in formed units - not counting anyone accompanying the column, of course.


What I believe to have happened here is simply that:

- Sears gives a number which reflects a Lost Cause source (as Harsh managed to trace the logic Sears was using and it is ultimately derived from a Lost Cause source) which gives a reduced strength for Lee's entire army - i.e. it gives about 50,000, of which DH Hill's reinforcing column is about a third or 17,000
- Hennessy has a handle on the actual strengths (effective) of the forces which fought at Second Bull Run, and adds them up after straggling and casualties to be on the order of 41,000 (which based on the effective strengths in Owen's ORBAT down to regiment/battery level is about right, though misses out Anderson's division which was the "reserve" and arrived later)
- The only way in which Hennessy can reconcile these numbers is to assume that the reinforcement column was 9,000 men in three formed divisions (which would make them extremely small) and effectively zero men in returned casualties with the reinforcement column (which we are told in other sources basically made good the casualties in Second Bull Run). He probably also assumed his strength figure for Longstreet was inclusive of Anderson, while in fact it's exclusive of Anderson (5700 effectives at the time).


The Second Bull Run ORBAT for Jackson's Command plus Longstreet's Command (all the individual units) plus Anderson plus Stuart plus Reinforcing Column adds to 75,700 on September 2. This is actually in Effectives, not Union PFD (we can tell because the matching Union ORBAT gives strengths which are clearly based on multiplying through PFD by 0.8 to get an estimate of effectives) and so the force Lee was using to advance towards Maryland may have been larger than 75,000 Union PFD.
 
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Thanks for this excellent work. For the Federals, at the start of the Maryland campaign, we should not forget the troops in Martinsburg (under White) and Harper's Ferry (under Miles). Together they would total around 13,000, although a large number weren't available for battle (e.g. sick, or non-combat staff). We could even include the troops in and around Baltimore led by the aging General John E. Wool, comprising maybe another 10,000 men. And then if things had gotten really bad, by mid- to late-September you had the Pennsylvania militia under John F. Reynolds available (OR says ~7,000 were already near Hagerstown at the time of the battle of Antietam, but most refused to budge from there), although they were as green as my front lawn after a particularly wet Spring.
 
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Thanks for this excellent work. For the Federals, at the start of the Maryland campaign, we should not forget the troops in Martinsburg (under White) and Harper's Ferry (under Miles). Together they would total around 13,000, although a large number weren't available for battle (e.g. sick, or non-combat staff). We could even include the troops in and around Baltimore led by the aging General John E. Wool, comprising maybe another 10,000 men. And then if things had gotten really bad, by mid- to late-September you had the Pennsylvania militia under John F. Reynolds available (OR says ~7,000 were already near Hagerstown at the time of the battle of Antietam, but most refused to budge from there), although they were as green as my front lawn after a particularly wet Spring.
This is true, though I discounted the Marrtinsburg/HF and Baltimore troops because they were at no point available to McClellan (at least until it was too late for them to be anything except captured). If Miles had managed the defence of the town more effectively though they could have held out for at least an extra day or two, which would have had enormous impact on the rest of the campaign.
 
This is true, though I discounted the Marrtinsburg/HF and Baltimore troops because they were at no point available to McClellan (at least until it was too late for them to be anything except captured). If Miles had managed the defence of the town more effectively though they could have held out for at least an extra day or two, which would have had enormous impact on the rest of the campaign.

Indeed. Given the leadership in Washington D.C. and their poor relationship with McClellan, it's hard to imagine scenarios where the troops in the capital and/or the troops I mentioned would be released to assist the Federal forces in Maryland. I wonder how many troops were left behind by Lee to defend Richmond? Unlike their foes, probably a tiny fraction of those that took part in the campaign.
 
Indeed. Given the leadership in Washington D.C. and their poor relationship with McClellan, it's hard to imagine scenarios where the troops in the capital and/or the troops I mentioned would be released to assist the Federal forces in Maryland. I wonder how many troops were left behind by Lee to defend Richmond? Unlike their foes, probably a tiny fraction of those that took part in the campaign.
My understanding is the following:

- McClellan asked for the Harpers Ferry forces to be released to him, but that was declined (at least until it was functionally too late to save them - at that point Halleck may have given them to him?)
- It is entirely reasonable that the capital defence force be large if the campaign is taking place near that national capital, though not as large as it was during the Maryland Campaign.
- Lee left, functionally speaking, GW Smith's division (minus Walker's two brigades) to defend Richmond. We have data for them for November.
Wise was in the defences of Richmond (at Chaffin's Farm), ditto Daniel (at Drewry's Bluff), the dept. of Henrico had enough troops for a field force under Winder in addition to troops in the garrison, and Pettigrew had a fairly large force at Petersburg. Add that lot up and convert it to PFD and it's about 10,400 infantry (in Wise/Daniel/Pettigrew) plus Winder/Dept. of Henrico (which I believe was on the order of 5,000, though very roughly and can't find the ORs I used to make the notes).

You can effectively view it that in July-September 1862 Lee had three "field corps" (Jackson's force of three large divisions in Jackson/Ewell/AP Hill, Longstreet's force of smaller divisions in Anderson/Hood/Evans/DR Jones/Kemper/Wilcox, and DH Hill's reinforcement column coming up from Richmond with his large division and those of McLaws (large) and Walker (small)) which he reorganized in mid-September into Jackson/Longstreet/McLaws/DH Hill with Walker as a flank guard.
Casualties at Second Bull Run and Maryland (largely in Maryland) amounted to enough that he then ended up with just the two field corps (in that he could fit them into two corps and wasn't forced to form a third) though my understanding is that he wanted three but couldn't countenance giving DH Hill a corps.
 
I believe McLaws was the other candidate to command a third corps, but was also rejected
My understanding is that Lee was testing McLaws in independent command in Maryland (McLaws being given a "corps" of about ten brigades, a quarter of Lee's army at the time), and was presumably unimpressed as McLaws then didn't get corps command again when Lee had to pick two new commanders post-Chancellorsville. Though it's also likely that it was a seniority issue, since DH Hill ranked AP Hill.
 
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