In reading Thomas Fleming's WWI tome Illusion of Victory, the ACW appears as an actor who repeatedly enters the stage on miscue and is then directed off.
First, there is the matter of the "Committee on the Conduct of the War." Republicans repeatedly tried to revive it under its precise ACW name and each time Woodrow Wilson succeeded in showing it off.
Same story in the matter of the U.S. Volunteers. Teddy Roosevelt and Leonard Wood stage multiple attempts to bring them back and Wilson keeps pushing them out of his way.
All the issues of preparedness, training, civil/military relations will strike the ACW reader as familiar.
A most interesting thing is this passage that author Fleming mined from an order issued by Pershing that explains maneuver warfare. The current Allied practice, Pershing says, is "marked by uniform formations, the regulation of space and time by higher commands down to the smallest details, and little intitiative."
Wow, shades of Col. John Boyd and his critique of second generation warfare. Nor does it get any more Boydian than this:
Open warfare had irregular formations, comparatively little regulation of space and time, and the greatest possible use of the infantry's own firepower to enable it to "get forward ... [with] brief orders" and "the greatest possible use of individual initiative."
Say hello to Boyd's third generation.
Boyd viewed the Civil War as first or second generation stuff, and my quibbles with that are here. Certainly, the horrific dedication to alignment, synchronicity, spatial management, and the micromanagement of undertrained subordinates all marked the ACW - and its failures were replicated in WWI. These vices govern much of our "best" military thinking today, especially in the Army.
Boyd viewed the Ludendorff tactics of 1918 as the beginning of maneuver warfare. Pershing called it open warfare. Small groups led by trusted, responsible, like-minded officers, acting irrespective of flanks or rear, losing communication with headquarters, bypassing strong points, moving ever deeper out of communication, and out of control, until the paralyzed and confused enemy collapses, flees, and surrenders. Lundendorff made it happen. Pershing got it "in real time." Boyd distilled it into a doctrine.
Pershing broke with the Civil War.
A tip of the hat to Fleming, who can recognize the good stuff among a general's many orders.