Why did John Bell Hood make such colossal mistakes at the end of the war?
A post of mine from an earlier thread about Hood and Atlanta:
Hood failed in several ways, the first and arguably most important being that he left the details to almost all of his major operations to subordinates. While this is a reasonable thing for a military commander to do, the Army of Tennessee had become, thanks to the machinations of Polk, Hardee, and Hood himself, an army where subordinates could not be trusted to accomplish their commander's objectives. If Hood himself was not present, then it wasn't going to get done the way Hood wanted it. Unfortunately, Hood was only physically present at one of the Atlanta campaign's battles, Bald Hill, and he only issued two direct orders during that battle. (He would ultimately not learn this lesson about the army, see the Affair at Spring Hill).
Hood had several opportunities, but was unable to execute them and he could not trust his subordinates to really execute them, with the possible exception of Stewart. Peachtree Creek was fumbled by a fuming Hardee, and Bald Hill was a combination of Wheeler and Hardee under-performing (though Hood did not manage his part of the field well), and Ezra Church was to S.D. Lee's overconfidence. Late in the siege, Hood sent away most of his cavalry under Wheeler to raid. Wheeler ultimately failed to cut Sherman's railway line and Hood effectively blinded himself when Sherman decisively swung his army group to cut Atlanta's last railroad south. The mismanagement of Jonesboro (a pointless battle as the rail-line would be cut by the Twenty-Third Corps regardless if the Army of the Tennessee was checked) speaks to itself, but Hood on bad intelligence recalled S.D. Lee's corps, an order that almost saw Hardee's isolated corps destroyed. However, the buck ultimately stops with the army commander, and that is Hood's fault.
There were staff issues (Chief of Staff Mackall quit over Bragg's presence and role in the new organization of the army, which meant he had to move his artillery chief Shoup to the chief of staff and move a colonel up to be the artillery chief), which conclude with the fact that Hood did not seem well prepared to evacuate Atlanta, and when he was forced to, the fires he set to his ammunition trains destroyed much of the city. So much equipment was destroyed or captured that Hood lost Shoup to a military inquiry (which would also have an impact at Spring Hill and Nashville).
Now, these are the things that Hood did. A very common claim is that Hood wasted 20,000 of his men in bloody and fruitless assaults around the city. However, this is not bared out by an examination of army returns and the context of campaign battles. Hood endured serious losses, but when Atlanta fell he was stripped of his cavalry corps, two infantry brigades (the Orphan Brigade and Baker's brigade), two cavalry brigades (Ferguson and McGuirk), four reserve artillery battalions (Williams, Martin's, Palmer's, and Waddell's) which explain the Army of Tennessee's reduced state when Hood invaded Tennessee that fall.
One thing that is clear is that Hood seemed incapable of learning from his mistakes, something that doomed him as an army commander and would fatally do him in Tennessee.