The Disastrous Appointment of Hood

On this date in 1864, Confederate President Jefferson Davis told Joseph E. Johnston, "... you are hereby relieved from the command of the Army and Department of Tennessee, which you will immediately turn over to General Hood."
Johnston had recently won a defensive victory at Kennesaw Mountain against an uncharacteristic frontal attack by US Major General William T. Sherman. But, to Davis' chagrin, Johnston was then compelled to continue retreating when Sherman reverted to using his superior numbers in flanking maneuvers north of Atlanta.
 Hood delivered as expected a new offensive strategy, launching an assault on the Army of the Cumberland under George Thomas on July 20 at Peachtree Creek, in which Thomas' fellow Virginia Unionist, US Brigadier General John Newton, played a key defensive role, and Thomas himself placed and directed an artillery battery. On July 22, Hood launched another attack against the US Army of the Tennessee, whose young commander, Maj. General James McPherson, was a friend of Grant. Both these Confederate offensive actions, and another on July 28 at Ezra Church, failed with heavy casualties, although the Union dead on July 22 included McPherson.
By the beginning of September, after various other engagements, Sherman captured Atlanta. He then set off on a more or less unopposed march to Savannah on the Atlantic coast, dispatching Thomas to defend Tennessee against a potential invasion by Hood.
Hood did set off for Tennessee, where he wasted his men's lives in an unsuccessful assault on Franklin. Then he advanced to Nashville, where his army was crushed by Thomas' counter-offensive in mid-December. The aggressive strategy of Davis and Hood had produced nothing but Confederate casualties.
The capture of Atlanta helped convince the northern electorate that the war was not stalemated, giving a necessary boost to Lincoln's re-election campaign. The political defeat of Lincoln was the Confederacy's last military hope, and, in hindsight, it is clear that only the retention of the highly competent Johnston could have given the Rebels any chance of holding Atlanta until after the election.
The Confederate Army of Tennessee was led during 1862 and 1863 by Braxton Bragg, whose tenure was about as disastrous as John Bell Hood's in 1864. Bragg, another friend of Davis, was finally relieved after his defeat by Grant at Chattanooga, but retained influence with  the president, advising him to replace Johnston, whom Davis detested, with Hood.
In Grant's Memoirs, he writes:
   "It was known that Mr. Jefferson Davis had visited Bragg on Missionary Ridge a short time before my reaching Chattanooga. It was reported and believed that he had come out to reconcile a serious difference between Bragg and Longstreet, and finding this difficult to do, planned the campaign against Knoxville, to be conducted by the latter general.
   … It may be that Longstreet was not sent to Knoxville for the reason stated, but because Mr. Davis had an exalted opinion of his own military genius, and thought he saw a chance of  'killing two birds with one stone.' On several occasions during the war he came to the relief of the Union army by means of his superior military genius."
Weakening Bragg's army by sending Longstreet to Knoxville was indeed a very foolish military decision, as was retaining Bragg so long in high command and influence -- as, for that matter, was attacking Fort Sumter in 1861, although that perhaps was more of a political blunder.
 But no military decision by Davis was more disastrous than his replacement of Johnston with Hood, the folly of which was recognized at the time by Sherman and other Union generals. Unlike Lincoln, the Confederate president lacked the capacity to learn from his military mistakes.