I finished Beatie's "McClellan Takes Command" last night (v2, AOP). It ran to about 567 pages, not counting the source notes and bibliography (which are fantastic).
Beatie develops material about McClellan's smaller military actions, which, taken together with the planning/replanning thread gives an entirely different picture from "All Quiet on the Potomac." His visit to the well-documented Ball's Bluff battle is especially worthwhile for its broader context of McClellan's policy of pursuing small Confederate withdrawals.
If I have a criticism, it is that the political material has been kept light, perhaps with military buffs in mind; there is more political material here than in any battle book on the market covering the same period, however this amounts to just about half of what is required. The management of military careers by various political patrons is outlined in just enough detail to help the reader make sense of what is happening within the commands but not in enough detail to depict the full pathology of the situation. McClellan was, like most top generals, both a beneficiary and victim of this system.
I am very impressed, nevertheless. A great reading experience.
Sorry to say that excerpts from the forthcoming Volume III, "McClellan's First Campaign," have been removed from Beatie's website.