Forces commanded by Major General Joseph Hooker, which had been sent from the Army of the Potomac, approached from the west and linked up with other units moving east from inside the city, capturing Brown's Ferry and opening a supply line to the railroad at Bridgeport.[212]
Grant planned to have Sherman's Army of the Tennessee, assisted by the Army of the Cumberland, assault the northern end of Missionary Ridge, preparatory to rolling down it on the enemy's right flank. On November 23, Major General George Henry Thomas surprised the enemy in open daylight, advancing the Union lines and taking Orchard Knob, between Chattanooga and the ridge. The next day, Sherman failed to achieve his mission of getting atop Missionary Ridge, which was the key to Grant's plan of battle. Hooker's forces took Lookout Mountain using an ingenious maneuver to flank the enemy, in unexpected success.[213] On the 25th, Grant ordered Major General George Henry Thomas to advance to the rifle-pits at the case of Missionary in an effort to help Sherman, after Sherman's army failed to take Missionary Ridge from the northeast.