Battle of Chattanooga, last fought by Grant and Sherman together. Why was its outcome significant ?

This battle enabled the Union to advance further into the Confederacy, especially to Atlanta.

http://www.nps.gov/hps/abpp/battles/tn024.htm

http://www.aotc.net/Chattanooga.htm

O.K. ...my answer was correct, but at this time, 1863, this Battle was also a Union victory ?

Yes.

The Battle of Chattanooga, fought from November 23 to November 25, 1863, during the American Civil War, was a significant turning point for several reasons. The outcome of the battle was significant because it opened up the Confederate heartland, helped to secure the Union's control over Tennessee, and set the stage for General William T. Sherman's march to Atlanta and his subsequent "March to the Sea."

To understand the significance of the outcome, we need to examine the context and the events leading up to the battle. Prior to Chattanooga, the Union had experienced a series of setbacks and stalemates in the Western Theater of the war. The Confederate Army, under the command of General Braxton Bragg, was holding Chattanooga, a crucial transportation hub and gateway to the deep South.

In September 1863, Union General William S. Rosecrans suffered a defeat at the Battle of Chickamauga, just south of Chattanooga. This pushed the Union forces back into Chattanooga, where they were besieged by Confederate troops on Lookout Mountain and Missionary Ridge. The situation for the Union Army was dire, with supplies and reinforcements running low.

Recognizing the gravity of the situation, President Abraham Lincoln responded by sending reinforcements led by Generals Ulysses S. Grant and Sherman. Grant was appointed as the overall commander, and his task was to break the Confederate siege and secure Chattanooga.

The turning point of the battle came on November 24, 1863, during the Battle of Missionary Ridge. Under Sherman's command, Union forces attacked and successfully captured the heavily fortified Confederate positions on Missionary Ridge, sending the Confederate forces retreating into Georgia. Simultaneously, on Lookout Mountain, Union forces under General Joseph Hooker achieved a significant victory.

The significance of the Union victory at Chattanooga lies in the strategic advantages gained. Firstly, the victory opened up a vital supply line and communication route between the Union's Western and Eastern theaters, allowing for better coordination of Union forces. This logistical advantage was crucial in future campaigns.

Secondly, the outcome gave the Union control over Chattanooga and effectively pushed the Confederates out of Tennessee. This secured the state and limited Confederate influence in the region, weakening their overall position.

Finally, Grant's success in Chattanooga enhanced his reputation as a military leader. It paved the way for his appointment as the commander of all Union forces and set the stage for Sherman to undertake his famous Atlanta Campaign and subsequent March to the Sea, which played a significant role in the eventual Union victory.

In summary, the significance of the Battle of Chattanooga lies in its role as a turning point in the Civil War. The Union's victory opened up supply lines, secured Tennessee, and set the stage for subsequent campaigns that ultimately brought the Confederacy to its knees.