A skirmish line and regimental line behind it—Union troops drilling at Chattanooga, circa January 1864. This gives a conception of how the soldiers of the Civil War ordinarily fought. A skirmish line moved ahead of the main regimental line, which charged upon order. The Union attack on Missionary Ridge must have looked something like this to watching Confederate soldiers.
From Miller's, Photographic History of the Civil War.

Lifting the Siege—The Battle of Chattanooga (continued)

MISSIONARY RIDGE, NOVEMBER 25. The decisive blow of the battle was at hand. Grant's orders for the morning of November 25 were as follows: "Sherman was directed to attack at daylight. Hooker was ordered to move at the same hour, and endeavor to intercept the enemy's retreat, if he still remained; if he had gone, then to move directly to Rossville and operate against the left and rear of the force on Missionary Ridge. Thomas was not to move until Hooker had reached Missionary Ridge."

Sherman began his attack, as directed, just after sunrise. His troops attacked Cleburne's Division frontally, but without success. All night the Confederates had worked at strengthening their position on Tunnel Hill which now formed the Confederate right. These field works gave good protection to Cleburne's men from enemy fire. The stubbornly fighting Confederates held their positions against repeated attacks by superior numbers. This fight continued until 3 p. m., and is a notable example of the value to a greatly outnumbered defending force of field works on a good position. Some Union troops did make a lodgment on the slopes of Tunnel Hill in the afternoon, but a Confederate charge drove them off. Cleburne's soldiers held the hill.

In the meantime, Hooker was in trouble—not with the enemy, but with Chattanooga Creek. He started for Rossville bright and early to get into position to strike Bragg's left. Stevenson's men who had evacuated Lookout Mountain during the night, had burned the bridge across Chattanooga Creek and had done all they could to obstruct the roads that Hooker needed to march to Rossville. Hooker lost 3 hours building a bridge across the creek and it was late afternoon before his men took their places on Missionary Ridge.

From his post on Orchard Knob, Grant realized that Sherman's attacks had failed to gain their objective and that Hooker had been delayed in reaching his assigned position. To relieve some of the pressure on Sherman, Grant ordered Thomas to move out against the Confederate center on Missionary Ridge.

The ridge that lay before the Union troops was rough and steep. It rose from 200 to 400 feet higher than the level ground at its base. Its steep slopes were broken by ravines, strewn with boulders, and dotted with stumps, the latter reminders of recently felled timber. The first line of Confederate breastworks was at the foot of the ridge. Some unfinished works had been built half-way up the slope. Finally, a third line of works was built on the natural, instead of the military, crest of the hill. Thus, Confederate fire from the crest could not cover some of the ravine approaches.

Four Union divisions—Baird, Wood, Sheridan, and R. W. Johnson, from left to right—started toward the ridge. The hard charging Union soldiers soon overwhelmed the gray defenders in the rifle pits at the base of the ridge. Scarcely halting, and generally without orders to continue, the men in blue charged up the ridge. They followed the retreating Confederates so closely from the rifle pits that the Confederates on the crest in many places hesitated to fire for fear of hitting their own men. It was not long before units of the Army of the Cumberland pierced the Confederate line in several places and sent Bragg's veterans reeling in retreat down the east slope of the ridge toward Chickamauga Creek. Sheridan pushed forward in pursuit of the retreating army, capturing men, artillery, and equipment. Even though the Confederate center had disintegrated, Hardee held his position on the Confederate right until darkness, and then began his withdrawal with Cleburne's Division covering the retreat. Bragg's army crossed Chickamauga Creek during the night, carrying out a surprisingly successful retreat.

During the evening of the 25th, Grant issued orders to Thomas and Sherman to pursue Bragg. The next morning, Sherman advanced by way of Chickamauga Station, and Thomas' troops marched on the Rossville Road toward Graysville and Ringgold. In the vicinity of Ringgold, Cleburne's Confederates held a strong position on Taylor's Ridge covering Bragg's retreat. Cleburne's men repulsed a Union attack, inflicting heavy casualties, until Bragg's army had successfully withdrawn southward, and then they followed. Union troops then occupied Taylor's Ridge. There the pursuit stopped.

This decisive Union victory raised the siege of Chattanooga.

The following tabulation of strength and casualties at the Battle of Chattanooga is based on Livermore's studies: