On the second day of the Battle of Chattanooga, Union forces under George Thomas charged up the steep, wooded slope of Missionary Ridge against orders to merely hold position, routing Confederate general Braxton Bragg's army. The victory, following the capture of Lookout Mountain the day before, opened the door for Sherman's 1864 march into Georgia and cemented Grant's reputation as the Union's most effective commander.
The assault on Missionary Ridge was supposed to be a limited demonstration—Union troops were meant to advance just far enough to relieve pressure on Sherman's flank. Instead, soldiers who had grown frustrated watching Lookout Mountain's fighting from a distance kept climbing, ignoring recall orders, and swept over Confederate rifle pits before continuing straight up the 400-foot ridge under fire.
Braxton Bragg's men, dug in along the crest, found their artillery nearly useless against the steep angle of attack; cannons couldn't be depressed enough to hit troops climbing directly below them. Confederate lines broke and fled, and Bragg's army retreated into Georgia in disarray. The rout at Chattanooga effectively secured Tennessee for the Union and set the stage for Sherman's Atlanta Campaign the following spring, a turning point that historians consider one of the war's most decisive Western Theater victories.