Lookout Mountain from Union works in Chattanooga.
From Harper's Pictorial History of the Great Rebellion.

Lifting the Siege—The Battle of Chattanooga (continued)

ORCHARD KNOB. The Union Army of the Cumberland had made its positions very strong during the time it was besieged by Bragg's army. One of its strong points was Fort Wood on an elevated Point east of the town. Thomas, according to instructions, sent Maj. Gen. Philip H. Sheridan's and Brig. Gen. T. J. Wood's divisions to level ground at Fort Wood and there formed them in line—Wood on the left, Sheridan on the right, with Brig. Gen. Absalom Baird supporting Sheridan. Brig. Gen. R. W. Johnson's troops held the trenches, and Maj. Gen. O. O. Howard's Corps, which had crossed from the north bank of the river, acted as the reserve.

Ar 2 p. m. on November 23, the lines of blue moved forward, driving the Confederate outposts and their supports back to the base of Missionary Ridge, and captured Orchard Knob, a low hill a little more than a mile in front of the ridge. The Union forces occupied the captured entrenchments and erected a battery on Orchard Knob. Except for occasional artillery firing, the fighting ended for the day.