After the fall of Atlanta, on September 1, the Army of Tennessee retreated southward, while General William T. Sherman's Federal forces took possession of the city. When General John Bell Hood realized that Sherman would not follow him, he decided to have his Confederate army strike at Sherman's supply line, hoping to draw the enemy northward. Through out the months of September and October, Hood struck at Federal garrisons, such as Acworth, Big Shanty, and ALLATOONA, wreaking havoc on Sherman's supply lines in Georgia and northern Alabama.
Initially, Hood's plan appeared to be working as Sherman gave chase with the bulk of his army, while leaving one corps to guard Atlanta. However, Hood's erratic movements hampered the receipt of badly needed supplies for his army. Additionally, the Southern army suffered from low morale, and it's officers expressed a general consensus that it was in no condition to turn and give battle to Sherman. With this in mind, Hood became increasingly convinced that a move into middle Tennessee would afford him several opportunities. He could strike at the Federal rail-line west of Chattanooga, drawing Sherman further north, or possibly reclaim the capitol of Tennessee, Nashville. To achieve his goal, his army would have to gather enough provisions, cross the Tennessee River, and move quickly before Sherman could send reinforcements to that region.
On October 25th, Hood's headquarters were located at the town of Somerville, thirteen miles southeast of Decatur, Alabama. Strategically located on the terminus of the Nashville and Decatur Railroad, where the Memphis and Charleston Railroad crossed, it was rumored that Decatur held a large quantity of badly needed supplies. No doubt, the Federal pontoon bridge that spanned the Tennessee River there made it an ideal place in which to serve as Hood's base for the upcoming campaign. On the 26th, the Confederate army began moving up and around the town, surrounding the Federal garrison, at the time commanded by Colonel C. C. Doolittle.
From Huntsville, Alabama, Brigadier General R. S. Granger, sent word to George Thomas in NASHVILLE that he needed reinforcements if he were to hold Decatur, and hurried there to take personal charge. Thomas, unconvinced that Hood's entire army was present at Decatur or that Hood would attack the works there, sent two regiments from J. B. Steedman's division, saying: "I will send you re-enforcements as fast as I can get them, but you must hold your position at all hazards." One of these regiments, the Fourth Michigan, would not arrive until October 28, bringing the Federal troops at Decatur to 2,000.
On the evening of the 26th, a torrential downpour soaked the hungry Confederates as they found themselves bogged down in knee-deep mud. And as they moved into position around the town on the morning of the 27th, they did so in a dense fog. Once the fog lifted, a defensive works consisting of two forts, 1600 yards of rifle pits and parapets could be seen. Notwithstanding the imposing defenses, Hood's soldiers went to work on building earthworks and emplacing artillery along the river and above the town. All of this work was "done on empty stomachs," complained one soldier, for Hood's supply system had all but broken down completely. The majority of the men had had nothing to eat in several days and desperately wanted the Federal supplies that were stockpiled in the town.
Hood spent the 27th getting his troops into position, and skirmishing broke out between the Federals and Confederates. While the newly appointed theatre commander, General P.G. T. Beauregard, met with Hood at his headquarters during the early evening hours, Confederate skirmishers were pushed forward to a ravine about 500 yards from the Federal line.
On the morning of the 28th, despite another dense fog enveloping the entrenchments, Federal skirmishers moved forward, under cover of the fort, and drove the Confederate skirmishers back. In this action, Granger reported the capture of 120 Confederates, mostly of Cheatham's Division, along with 40 enemy killed and wounded. Granger also reported the capture of 5 officers.
Though Hood's entire army of 23,000 were now encircling a garrison of 2,000, Beauregard argued that to continue an attack on fortifications would be too costly in the loss of life. In addition, Federal gunboats had arrived to patrol the river and prevent Hood's army from crossing. Weighing these considerations, as well as being low on ammunition, and the men needing to get provisions, Hood elected to attempt a crossing at Bainbridge, some forty-miles west of Decatur. Arguably, Hood's decision to abandon Decatur would appear foolish, but even the common soldier recognized the wisdom in the decision by commenting in his diary: "A wise self restraint, for overwhelming in number though we were, a good sized and gallant garrison was there, and it was useless to throw away a number of valuable lives, when a flank movement would compel them in a few days to retire; " adding, "There we lay taking their fire but not returning it, for orders were "not to start an artillery duel or anything that would bring on a fight."
Encouraged by the success of their earlier action, Granger sent another force out of the fort on the evening of the 28th. In his telegram to Thomas on the 29th, Granger reported the following: "In the evening we made another sortie, spiking a couple of guns, and making 14 more prisoners. In this skirmish we lost 40 killed and wounded. Our loss altogether up to this time amounts to 80. We blew up 4 caissons and dismounted 2 pieces of artillery. We killed and wounded a very large number of the enemy, full 500. About 4 o'clock this morning they began to leave in the direction of Courtland. I have been probing them at different points all day, finding them in force, until 4 o'clock this evening, when our forces carried their last line of rifle-pits. Enemy evidently believed us to be in very strong force here, judging from what their prisoners have stated."
Under cover of darkness, the Army of Tennessee moved out of Decatur on October the 29th, marching westward in the direction of Bainbridge. Hood would ultimately cross the Tennessee River west of Bainbridge, at Florence, Alabama.