Yet his methodology gives a similar result to Harsh's methodology.
I do not own a copy of Harsh's works, but per
http://www.brettschulte.net/CWBlog/...l-level-orders-of-battle-second-bull-run-oob/ the figure of 75,687 is for September 2 - two days before the vanguard of the ANV entered Maryland, and thus before any men who (for whatever reason) fell out of the ranks before the army entered Maryland have been subtracted.
That really doesn't answer one way or another how many men were actually present in Maryland in gray.
And the evidence Thorp uses to support his position actually suggests less than that were present for duty, not his 75,000+.
Steiner said (copy/pasted from a text version of the document, so pardon any errors in my transcription)
"Wednesday, September 10. At four o clock this morning the rebel army began to move from our town, Jackson's force taking the advance. The movement continued until eight o clock P. M., occupying sixteen hours. The most liberal calculations could not give them more than 64,000 men."
and
"Thursday, September 11. General Hill s division, numbering about eight thousand men, marched through the streets, on their route westward, this morning."
https://archive.org/details/reportlewissteiner00steirich
That means that the
highest number for those Steiner saw marching by - assuming his count is accurate, which is not something I would put money on under any circumstances given the difficulty of avoiding double counting - was 72,000. And quite possibly less. But on top of that, it is the total number of men marching by. It is not the number of men present for duty, but at best the army's aggregate present.
Per the return for September 22 (I could pick another for comparison's sake, but it is the closest to September 10 we have, and thus hopefully more representative of the number of men "present but not present for duty" than a figure from earlier or later): The army's "aggregate present" in those units whose strength is reported is 41,529 men. The present for duty figures for those units reported is 36,418. Subtracting Walker's division (which did not march through Frederick) for a more precise comparison, we have 32990 present for duty, 37649 aggregate present.
If the same percent of present for duty out of the aggregate present was true of Steiner's 72,000 tops figure, we'd have around 63,090 men present for duty out of those marching by, plus the troops not counted by Steiner.
Stuart's cavalry (noted, at least in part, by Steiner, but whose numbers are not estimated) plus Walker's two brigades do not come anywhere near twelve thousand men present for duty.
And the other eye witness reports are all over the place, and some seem rather secondhand.
They cannot be used to confirm that Lee had not suffered an appreciable amount of men falling out of the ranks between September 2 and September 10, let alone between September 2 and September 17.
Point #2: Thorp gives the figure of present for duty in the entire army (except for the reserve artillery and cavalry) as the infantry present for duty on September 22. As the September 22 return specifically includes to two battalions of artillery (Walton's and Lee's), and it is reasonable to assume that the divisions include the artillery attached to them as well as the infantry, one wonders how closely he actually paid attention to the return in question.
Was Lee's army on September 2 larger Sears described it? Very probably (with limited records I'm reluctant to say "certainly"). But does that mean that McClellan actually had to deal with 70,000+ Rebels in Maryland? No. Thorp has given nothing to give that claim any more credibility than the opposite extreme of Lee having closer to 35,000 than 40,000 all totalled on September 17, and that claim can be poked full of holes without even relying on the latest research (even if possibly a dry read, it would be nice to see Harsh's work at least referenced as a more recent study than Sears in something written in 2012).
Bringing the