According to historian Eric Jacobson, the Army of Tennessee had 28,000 infantry and 5,000 cavalry when it arrived in middle Tennessee in late 1864. Hood took over the Army of Tennessee in July from Johnston. There were 8,000 Federals garrisoned at Nashville at the time.
Hood would lose at least 7,500 at Franklin (30 Nov 1864) and another 6,600 at Nashville, two weeks later. When the Army of Tennessee retreated back to Pulaski in mid December 1864, the army was reduced to but a shadow of its former self.
Confederate General, John Bell Hood
Hood was the fifth commander of the Army of Tennessee. He commanded the army from July 17, 1864, until January 15, 1865. Many historians say his recklessness destroyed the Army of Tennessee. In just six months (July 1864 – December 1864) Hood lost at least 30,000 men* at a time when the Confederate army, and especially the Army of Tennessee, was in desperate need of men.
*Casualty estimates are based on the conservative figures as reported by the National Park Service. Here are the major engagements Hood was involved in from the time he became commander of the Army of Tennessee.
July 20 Peachtree Creek – 4,796
July 22 Atlanta – 8,499
July 28 Ezra Church – 3,000
Aug 31 – Sept 1 Jonesborough – 2,000
Nov 30 Franklin – 6,261
Dec 15 Nashville – 4,462