The Civil War author, almost without exception, makes a number of obvious errors in describing the Union management of intelligence.
(1) Mistaking information passed along for an intelligence estimate. If the commander is passing along raw intelligence, that is not an estimate. You often have to dig out the reference to see what the author is (falsely) ascribing to the commander.
(2) Mistaking passed-on intelligence for what the commander believes. I notice in pass-along information all sorts of hedges and caveats from the commander that the historian strips out of the account. Be vigilant, reader.
(3) Apples equal oranges. The commander is estimating one thing but the historians are counting something else as if it were the object of the commander's estimate. This sets up those commander = idiot arguments that so entertain writer and reader.
(4) We now know the true numbers. If there is a "most embarassing moment" for historians it's when they claim numerological Truth in order to castigate a commander for not knowing what historians (erroneously) think they know now.
(5) The mistaken estimate is a personal failure. The deep reader knows better - it is a universal failure.
(6) Better estimating would lead to better campaigning - Is there a single example of this in the Civil War? Is it not said of Grant that after a certain time he ignored estimates in order to become effective?
(7) These estimates could not be true! The historian here has experienced a failure of imagination and a failure of research - both at once.
(8) Lots of zeroes. The well rounded pop historian likes a well-rounded number. Since it is impossible to know what the actual figures are, it is madness to try to calculate with exactitude! Not to say we can't claim Truth for our well-rounded number...
(9) Rely on the payroll muster for your own analysis. The payroll muster is the absolute first stop for anyone doing a count. It is also the last stop for the overwhelming majority of historians. All those elected company commanders can be relied upon absolutely to render an accurate census on pay day. That's what they were elected for.
(10) Rely on the commander's reported strength figures. It is simply not possible that a commander would put a political shading on his numbers. This is, after all, military history.