In late September 1863, Union Major General William Roscrans’ Army of the Cumberland invaded Georgia from Tennessee and was decisively defeated at the Battle of Chickamauga. Only the personal leadership of MG George H Thomas, nicknamed the “Rock of Chickamauga” by Ulysses S Grant, prevented the Army of the Cumberland’s total destruction. Rosecrans retreated to Chattanooga, Tennessee where Confederate General Braxton Bragg occupied the heights above the city and prepared to starve out the Union troops.

By November 1863, President Lincoln and General Grant realized that the war would only end with an invasion of the Deep South. The first step, and Gateway to the South, was the strategically vital rail hub of Chattanooga, then under siege by the Confederates. On 23 and 24 November, William Sherman’s Army of Tennessee maneuvered on Bragg’s positions but it was a disaster. The only successful action was Joe Hooker’s fight in Lookout Valley which nearly unhinged the Confederate line. However, Sherman’s troops could not capitalize on the near-success. At the end of the day, the entire army was divided and neither Hooker nor Sherman could support each other. The Union Army was in a terrible predicament the next morning. In desperation, Grant asked Thomas (who replaced Rosecrans as the commander of the previously discounted troops inside Chattanooga) for a supporting attack against the heavily entrenched Missionary Ridge in order to take some pressure off of Sherman. Grant wasn’t expected much from the “demoralized” and “defeated”, albeit fresh, Army of the Cumberland.

On Wednesday afternoon, 25 November 1863, Thomas’ Army of the Cumberland stepped out of the sleepy town of Chattanooga to attack Missionary Ridge. Assaulting the entrenched troops at the end of the long open slope was a tough, nearly suicidal, assignment and they knew it. But to the Army of the Cumberland, the entire Union Army was in this position because of their failure. Now they were given a nearly unheard of second chance.

Their Day of Redemption was at hand.

First at the quick step, then at a double, then in ones and twos they sped up and broke ranks toward the Confederate lines. Soon entire regiments were in a full sprint and fixing bayonets on the run. Thomas’ blue tide swept over the first line of trenches as if they weren’t there. Then it clawed its way up the steep slope toward the second, with soldiers shouting “Chickamauga!” at the top of their lungs. The unstoppable Army of the Cumberland soon took the second trenchline and broke the rebels. Not stopping, they continued over the top of Missionary Ridge and down the far slope. In full view of a flabbergasted Grant and Sherman, Thomas’ soldiers impossibly cleared the ridge of Confederates, which forced Bragg to retreat.

The news of the dramatic victory would reach Washington DC the next day, where President Lincoln was celebrating America’s newest national holiday, the first official Thanksgiving Day.