The Peninsula What we know about strengths on the Peninsula


Feb 18, 2017
This will be an attempt to summarize or collate the information which we have available in order to estimate the strengths on the Peninsula, for both the Union and Confederate armies. I will mostly be focusing on the Confederates simply because for the Union we have much better information (in the shape of properly filled out strength reports) in many cases.


The following terms are used:
PFD - Union regulation Present For Duty.
Effectives - the stripped-down count of effective soldiers used principally by the Confederates, such as in Joseph E. Johnston's command (the Army of Northern Virginia - he was the one who made the reporting change from regulation PFD) and labelled by them as "PFD". The rough rule of thumb is that 5 effectives = 6 PFD.
Aggregate Present - this term was largely but not entirely the same in both armies, and is a larger measure than PFD. It is effectively the men present with the army, though it does not count non-soldiers (such as the black men both slave and free who formed a large part of JE Johnston's logistics train).
Regiments of All Arms - this is essentially the number of companies in a force divided by ten. With care taken to track it can be determined nearly exactly, and is a valuable check on the quality of estimates.

Union strengths:

The strength of the Union force which went to the Peninsula in March and April can be best determined based on the strength report of March 31, on the following calculation:

The regular cavalry (under Cooke) was reported on March 31 as being 2,601 men PFD. This reflects the 5th US, 6th US, 6th PA, 1st US, 8th PA, Barker's Illinois Dragoons and the Oneida company, plus possibly the 2nd US Cavalry, which is about five regiments (1st US and 2nd US add to one) and odds and sods; this implies approx. 500 PFD per cavalry regiment.
All of these units arrived.

The corps cavalry brigades at the time were:
1st Corps: 2 regiments (1 NY, 2 NY) of which the 1st NY arrived with Franklin
2nd Corps: 2 regiments and 1 squadron (3 NY, 8 IL) of which 8th IL arrived
3rd Corps: 2 regiments (3 PA, 1 NJ) of which 3 PA arrived
4th Corps: 3 regiments (1 PA, 5 PA, 4 NY)
In addition, a battalion of the 6th NY arrived mid-April, a battalion of the 11th Pennsylvania arrived early-June, and a battalion of the 4th PA was arriving at the start of the Seven Days.

Of the infantry corps:
None of 1st Corps went, except Franklin's division later (1/3 of 1st Corps as of March 31). McCall's division arrived in mid-June and it is enumerated separately on the June 20 report.
Two divisions of 2nd Corps went (2/3 of 2nd Corps as of March 31)
All of 3rd Corps infantry went
All of 4th Corps infantry went

In addition, the regular infantry and the reserve artillery went.

The best way to estimate the strength which went to the Peninsula would be to:
- Deduct 500 PFD per cavalry regiment
- Reduce the strength of the 1st and 2nd Corps (to 2/3 for 2nd Corps and 1/3 for 1st) to get the strengths of the infantry forces sent.
- Add cavalry as separate entry

Reported PFD
Cav rgts​
- cav​
Fraction went​
1st Corps​
2nd Corps​
3rd Corps​
4th Corps​
Cavalry and reserve artillery​
Extra cavalry by May 10​

The principal error in this estimate is related to the size of the cavalry regiments.

Once we move past the Yorktown siege, our data is much more solid. We have good PFD reporting for e.g. June 20 and July 10, and the only caveat that needs to be borne in mind is that while on the June 20 return the forces at Fort Monroe and environs are carried on McClellan's returns this does not reflect the strength of his field army itself.

McClellan's strength in ROAA:

3rd Pennsylvania Cavalry: disembarked 28th-31st March (12 coys)
5th US Cavalry: disembarked 3rd April (10 coys)
1st US Cavalry: disembarked 4th April (4 coys)
2nd US Cavalry: disembarked 4th April (7 coys)
6th US Cavalry: disembarked 4th April (12 coys)
6th Pennsylvania Cavalry: disembarked 12th April (12 coys)
8th Pennsylvania Cavalry: disembarked 13th April
3rd Bn, 6th NY Cavalry: around mid-April (3 coys left camp on 31st March and the 4th on 7th April. They rode out the storm for three days on ship and then landed at Shipping Point, so post 12th April)
(Sqn, 4th US, McClellan Dragoons and Oneida Coy probably also disembark here)
8th Illinois Cavalry: disembarked 1st May
1st New York Cavalry: disembarked 10th May
11th Pennsylvania Cavalry: 5 coys arrived early June at WHL.
4th Pennsylvania Cavalry: arrived at White House Landing 24th June, only one battalion disembarked before the crisis.

Total cavalry coys assuming all full regiments not described above are 12 coy: 102 by Seven Pines, 111 by Seven Days

Infantry formations:

2nd Corps 28.8
1 bty +
12 regiments infantry and 4 batteries artillery in Richardson
12 regiments infantry and 3 batteries artillery in Sedgwick
(did not go: 11 regiments infantry and 3 batteries artillery in Blenker; 72% of corps went)

3rd Corps 43.2
3 batteries +
16 regiments infantry and 2 batteries artillery in Porter
14 regiments infantry and 4 batteries artillery in Hooker
12 regiments infantry and 3 batteries artillery in Hamilton

4th Corps 42.2
14 regiments infantry and 4 batteries artillery in Couch
13 regiments infantry and 4 batteries artillery in Smith
14 regiments infantry and 4 batteries artillery in Casey

21 batteries in art reserve, so 2.1 rgt

Sykes 8.4
7 inf regiments and 14 slack coys, so 8.4 est.

Other HQ: 3.7
2.5 engineers
1 siege art
0.2 provost

Franklin: 12.4
12 regiments inf and 4 btys art
(did not go at this time: 12.3 in King, 13.4 in McCall; Franklin is 32.5% of 1st Corps)

McCall: 13.4
13 regiments inf and 4 btys art

Other reinforcements in June: 10 reg
2nd Del
16th MA
2nd NY
20th IN
101st NY
1st NY
99th PA
1st MI
20th NY
10th NY
Original 2nd​
Original 3rd​
Original 4th​
Art Res​
Other HQ​
Other June​

The Confederates, of course, are much more of a problem.

Confederate strengths at Yorktown

The best source of information we have for the Confederate strength at Yorktown is a report compiled in May and backdated to late April. It gives the strengths by regiment of almost every individual unit which was at Yorktown itself; this means that all that remains is to estimate the few remaining units (principally these are the reserve artillery, Pendleton's 36 guns and the Washington Artillery, both estimated here at 20 gunners per gun in keeping with the typical strength per gun given for the batteries reported). The sum total of all of these is 58,443 (all of whom had arrived by April 22), and these represent about 100 regiments of all arms and thus the strength is about 584 men per regiment as of the end of the siege. As this was compiled under JE Johnston we should expect it to be Effectives.
On around May 20 McClellan's forces (with ca. 151 regiments of all arms) had around 103,000 PFD, which implies a figure more like 682 PFD per regiment; we can thus buttress the idea that the Yorktown figures represent Effective strength.

We can then track the arrival dates of all the units (for example, Wilcox's 19th MS and his artillery arrived on March 29; the 9th, 10th and 11th AL arrived on March 31) and get a summary.

With this in mind, estimated Confederate strengths (PFD) at Yorktown on certain dates:


Notably on the 25th Magruder's strength in Effectives (Confederate PFD) was 11,500, which is the most likely cause of his later claims of lacking in strength. He was certainly that weak on that date, but in the ten days between then and the initial contact he recieved 7,219 effective infantry, 60 effective artillerymen and 700 effective cavalry.

The above analysis has not attempted to take into account any sickness that may have taken place in the trenches, assuming that the units remained static in strength throughout April.

Strengths from Yorktown to Seven Pines

Just over 100 regiments of all arms marched out of Yorktown (102), and these were joined in May by another 35.7 regiments of all arms (principally consisting of Huger's 11.9 from Norfolk and what would become AP Hill's division, totalling 21 regiments not part of Huger). These forces however also suffered casualties at Williamsburg.

The first-order estimate of what we should expect to see is a 33% increase in total PFD, minus the amount of casualties suffered at Williamsburg and the minor battles (for a total of 1,682 at Williamsburg and 48 at Eltham's Landing) resulting in an estimated 91,800 PFD facing McClellan around Richmond for the period of Hanover Court House and Seven Pines. This force is quite close in strength to McClellan's own total around this period, and it should be because the regimental counts are quite similar (~151 ROAA for McClellan with 103,000 PFD and 682 men per regiment, ~138 ROAA for Johnston with 91,800 PFD and 655 men per regiment.)

Strengths at the Seven Days

For the Seven Days, Jackson came down from the Valley, and in addition a significant number of new regiments joined what was now Lee's army. There are four ways to approach the strength at the Seven Days.

Regiment counting

Going by pure regiment counting, there were 204.7 regiments of all arms forming the field army at the Seven Days, plus the Richmond garrison forces (which helped shape the battlespace June 25-7 and numbered 8.6 regiments of all arms, plus 2.5 militia regiments of all arms, but minus 0.5 because the 12th Bn Louisiana Heavy Artillery was at Yorktown). This totals 215.3 regiments of all arms.
McClellan had 175 regiments of all arms at Richmond and 105,825 men PFD, meaning a strength on that date of 604 men PFD per regiment. The same average strength per regiment for Lee would put him at 130,200 men PFD.


Harsh in Confederate Tide Rising gives a list of the strengths of various components of the Seven Days force (and gives 215 regiments of all arms at Richmond). He gives:

Total 112,200 men
Johnston's old army (129 ROAA and 69,000 men) (this appears to be the Seven Pines force minus perhaps Whiting)
Jackson (35 ROAA and 15,904 men)
Dept. of NC (33 ROAA and 22,048 men) of which half (17 regiments and therefore 11,358 men) had arrived
Dept. of Henrico (19 ROAA and 11,288 men)
And in addition there are 15 ROAA not counted, which by subtraction must be 4,650 men.

This however appears to be adding formations with different strength definitions:
The Johnston one is 535 men per ROAA, which seems low to be PFD given that McClellan on the same date had 604 men PFD per regiment (and the Confederates were in a better garrison position). This may be Effectives.
The Jackson one is 454 men per ROAA, which also seems low to be PFD.
The Dept. of NC numbers give 668 men per ROAA, which seems reasonable to be PFD.
The Dept. of Henrico gives 594 men per ROAA, which also seems reasonable to be PFD.
And the 15 other ROAA by subtraction are 310 men per ROAA, which is far too low.

Changing these estimates so that:
Johnston's old army is increased to 600 men PFD per regiment (a 12% increase)
Jackson's force is multiplied by 6/5 to convert to PFD (making them 19084 men at 545 men per regiment)
And the 15 other ROAA are treated at 594 men PFD per ROAA (like the Dept. of Henrico)
results in a total of 128,024 men PFD at 595 men per regiment.

Second Bull Run campaign

In an order of battle constructed by Schulte for the Northern Virginia campaign, the strengths of all units in theatre are given. This strength, based on comparisons with four separate AotP divisions, is 0.8 x PFD, which means that taking the strength of each unit when first given by Schulte (before battle casualties) and dividing by 0.8 (multiplying by 1.25) will give an estimated PFD for after the Seven Days.
This method will (erroneously) include the regiments which joined Lee's army after the Seven Days (26.1 regiments of all arms) and any forces Jackson left in the Valley (mostly cavalry) and will also not include the formations left behind by Lee to defend Richmond. Ignoring those factors however we have:

27988 (Jackson's army of the Valley, Aug 1) - includes the Laurel Cavalry and Ashby Horse Art
23608 (Longstreet's command Aug 18) - JR Jones, Hood, Evans, Kemper, Wilcox
6150 (Anderson's division, not reported under Longstreet)- Anderson
2223 (Stuart's command not counting the Laurel cavalry) - F. Lee, Stuart Horse Art, Pelham Horse Art
1509 (Hamton's cav Sept 2) - Hampton, Washington Horse Art
24071 (DH Hill's reinforcing column Sept 2) - DH Hill, McLaws, Walker

Total 85,549 effectives (107,000 PFD)
With Seven Days casualties: 127,000 PFD


This might sound weird, but it's based off some interesting information noticed in a book from the turn of the 20th century.
Essentially, this author noticed that Lee was complaining that he didn't have enough officers for his regiments after the Seven Days, at a time when he had already sent Jackson (but not AP Hill) off back to the north.
On July 20, Lee had 4,333 officers in his army (not counting Jackson) which was up 12 regiments on the Seven Days.

As it happens, McClellan's report for the 10th of July (which includes Fort Monroe and is up nine regiments on Seven Days strength) has a headline number of 4,327 officers PFD. Looking at all McClellan's infantry units gives a range of 19-25.3 enlisted men per officer, with the average being 23 (so officer number * 24 is a rough estimate of PFD strength for an infantry formation).

The same figure for the whole of McClellan's force, sans Fort Monroe, is about 22.3 (so officer number * 23.3 for whole-force PFD) and including Fort Monroe makes it 22 men per officer (so officer number * 23).

Based on this estimate our first-order calculation for Lee's strength on July 20 would be on the order of 99,700-104,000 PFD.

Doing the same calculation with Lee's infantry units using the July 20 strengths means he comes out as about 13.5 to 18.5 officers per man (averaging 15.2), which is far lower (and definitely supports the idea he's not using the same measure of PFD). Since the AotP corps in March pre-Peninsular campaign were in the range 20.5-23 officers per man (average 22.3) it looks like the reason for the discrepancy is not that McClellan had ended up with a disproportionate number of non-PFD officers; it must be the case that Lee's officer count is proportionate (or low), rather than high.

This means we can estimate Seven Days strength as:

Same number of men per officer as McClellan, for Lee's July 20 strength
+ Jackson and Ewell from Schulte
+ 7 days casualties
- reinforcement regiments (which had arrived by July 20 but which were not at the Seven Days)
- recovered Confederate casualties

4333 officers at Richmond July 20, x 23 by comparison with McClellan = 99,700 PFD
Jackson and Ewell August 1 (7500 + 5700) / 0.8= 16,500 PFD (this is from the Schulte ORBAT and assumes no cavalry went north with Jackson)
Seven Days casualties 20,000 (assume PFD)
12 reinforcement regiments (9152 * 12/13.4) = 8,200 PFD <- this is the reinforcements Lee got post-Seven-Days and by July 20, calculated by comparison with the 13.4-regiment Pennsylvania Reserve division on June 20

Estimate of recovered casualties based on Union...
5th Corps on June 20 exc/ of attached cavalry is (3+493+10940+268+5477+85+2023) (PFD main 5th Corps) + 382+9132 (McCall) for 28803 total
Suffers 56+939 killed and 101 + 2700 captured (3796 unrecoverable casualties) n.b. cav casualties ca. 40 overall, do not affect conclusion
Suffers 194+3611 wounded (3805 recoverable casualties)
Strength July 10 is 20203 + 817 for 21020 total
If no wounded recovered, would be 21202
So recovered casualties 10 days after end of fighting are negligible and/or compensated for by sickness

Will assume 2,000 Confederate casualties recovered by July 20, to argue a fortiori


99700 + 16500 + 20000 - 8200 - 2000 =
126,000 PFD

This leads to a general picture of Confederate strength at Richmond in the Seven Days of between 125,000 and 130,000 PFD.
Last edited:


Feb 18, 2017
Things which could be done to improve the above: firming up the derivations of the ROAA counts for the Union to see if this affects the results (ed: done)
Last edited: