When Bragg was removed from command of the Army of Tennessee, the successor reorganized and removed a corp commander...and Hood finagled his way into the position.
He then proceeded along a long path of mediocrity, being unable to efficiently coordinate a corps-sized unit.
But that didn't stop him from throwing himself into army politics, defaming his seniors and positioning himself for command.
Which, through his friendship with the President, he got.
And he then killed his army. He took over a force of 60,000...and ended the campaign with a force of 30,000...50% of his force he lost in poorly conceived and totally uncoordinated attacks on entrenched Union positions.
But he wasn't done, no. He was friends with Davis...and with Davis's new mouthpiece, Bragg.
His new plan, was to take what was left of his army and invade Tennessee to put himself across Sherman's supply line. Sherman didn't care, he didn't need a supply line.
So Hood marched his forces, largely unsupplied due to Hood's incompetence (Beauregard noted that his supply centers were full of food and clothes, but they never left Alabama), into the middle of a dead country, stripped by three summers of war, against superior Union numbers in the hands of their finest defensive generals (Scofield and Thomas).
While what appears to be Hood's suicidal aggression around Atlanta may have been an accident of circumstance, at Franklin it was unmistakable. He threw his forces against deeply entrenched positions which were well supported by smoothbore artillery. He ordered several small-scale attacks over two miles of open ground. He had less than 30,000 at the start, and lost around 7000 of them. Union forces withdrew; and he pursued, thinking he had won. Then before Nashville he tried to engage in siege operations against a force twice his own. Union forces swarmed down from their positions and his army effectively ceased to exist.