the city, capturing Brown's Ferry and opening a supply line to the railroad at Bridgeport. 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. 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. Four divisions of the Army of the Cumberland, with the center two led by Major General Philip Sheridan and Brigadier General Thomas J. Wood, chased the Confederates out of the rifle-pits at the base and, against orders, continued the charge up the 45-degree slope and captured the Confederate entrenchments along the crest, forcing a hurried retreat. The decisive battle gave the Union control of Tennessee and opened Georgia, the Confederate heartland, to Union invasion. Grant was given an enormous thoroughbred horse, Cincinnati, by a thankful admirer in St. Louis. On March 2, 1864, Lincoln promoted Grant to lieutenant general, giving him command of all Union Armies. Grant's new rank had only previously been held by George Washington. Grant arrived in Washington on March 8, and he was formally commissioned by Lincoln the next day at a Cabinet meeting. Grant developed a good working relationship with Lincoln, who allowed Grant to devise his own strategy. Grant established his headquarters with General George Meade's Army of the Potomac in Culpeper, north-west of Richmond, and met weekly with Lincoln and Stanton in Washington. After protest from Halleck, Grant scrapped a risky invasion plan of North Carolina, and adopted a plan of five coordinated Union offensives on five fronts, so Confederate armies could not shift troops along interior lines. Grant and Meade would make a direct frontal attack on Robert E. Lee's Army of Northern Virginia, while Sherman—now chief of the western armies—was to destroy Joseph E. Johnston's Army of Tennessee and take