Christmas Presents

 In supplementary material to the timeline, TFSmith states:

In terms of a multi-front war, it is worth considering the scale of the US mobilization that had begun in April of 1861 (500,000+ troops, PFD, by the winter of 1861-62) and the extent of their operations ...

The numerical value given is unsupported by evidence, at best.

The numerical value given is unsupported by evidence, at best. The 31 December 1861 return
http://ebooks.library.cornell.edu/c...o=waro0122;didno=waro0122;view=image;seq=0787
gives 425,405 men present for duty. The footnote also states that (possibly only for Halleck) the column of "present for duty" represents everyone present, including "for duty", "on extra or daily duty","sick" and "under arrest".

Buell states in January 1862
http://ebooks.library.cornell.edu/c...o0007&q1=strength&view=image&seq=579&size=100
that of his 72,502 troops only 46,150 are actually ready to take the field; the reason this is important is that it shows his 72,309 PFD in the 31 December 1861 report roughly equates to the strength of troops present, not the strength present and effective.

The next biannual return we have is from 30 June 1862
http://ebooks.library.cornell.edu/c...o=waro0123;didno=waro0123;view=image;seq=0197
which gives the total strength in PFD to be 432,609. This is after a few battles, including Shiloh (April), but before the Seven Days.

Thus the question is - with the first large battle of the war being in April, did the US have enough men to equal 500,000 Present For Duty at any point?

If we assume that the number present for duty in January is a maximum for the regiments currently with the army (because men deserting over the winter and becoming ill would tend to reduce the numbers per regiment on average) then we can look at the number of regiments mustered in before the end of March and see what their average per-man count would need to be to reach the magic 500,000 number.

In January 24 infantry regiments, 3 cavalry regiments and 35 artillery companies (3.5 regiments) mustered in.
In February it was 21 infantry regiments, 6.5 cavalry regiments and 12 artillery companies.
And in March it was 20 infantry regiments, 2 cavalry regiments and 23 artillery companies.

This totals to 83.5 regiments. To make up the numbers the average regiment would need to be 900 men strong.
While this may be theoretical strength, in practice regiments very quickly shrank below this number:
http://ebooks.library.cornell.edu/c...aro0123;view=image;seq=872;page=root;size=100
In December of 1862, the Union Army had 816 regiments of infantry totalling 573,000 present for duty; this is about 700 men per regiment. (The numbers for cavalry are the same.)

Examining the returns of the surgeon-general (which tracks those men who were fit for duty - a number smaller than the present for duty) we see a trend as such:

1861-07 69118
1861-08 109054
1861-09 162217
1861-10 252637
1861-11 296625
1861-12 336745
1862-01 343572
1862-02 316568
1862-03 314961
1862-04 395713
1862-05 388492
1862-06 367952

These are mean strength by month. The April strength is certainly higher than that for December or June, but only by about 12 percent over their average (which would make the PFD strength at the end of April, pro rata, roughly 480,000; not only is this not 500,000 but it is also a month late).

The final confirmation comes from the report of 15 February 1862 on the number of troops in each military department:
http://ebooks.library.cornell.edu/c...aro0122;view=image;seq=902;page=root;size=100
which gives the total on this date to be 490,972 "in service". This is probably Aggregate Present - compare the December 1861 Aggregate Present of the Army of the Potomac (208,604) with the number in this report (211,965) to see the similarity, though it may also represent Aggregate Present and Absent.
Although the 490,972 figure does not note six specific regiments and a few supplements (26th Mass, 9th Conn, 4th Mass Battery, 12th Maine, Eastern Bay State, three companies of cavalry, 7th Vermont and 8th Vermont) at most this increases the tally by perhaps 6,000 Aggregate Present.

With a total of approx. 497,000 Aggregate Present (at most) it is impossible to have 500,000 Present for Duty in February.


Thus we can see that it is very unlikely, bordering on impossible, for the Union to have historically had "500,000+ troops, PFD, by the winter of 1861-2" even if "by the winter" means "by the *end* of the winter". This is just another overestimation of Union strength, and one which is particularly important as the best estimate of the discrepancy is roughly equal to the entire US Army that invades Canada.