Sherman proceeded to Chattanooga, where Grant instructed him to attack the right flank of Bragg's forces, which were entrenched along the Missionary Ridge. On November 25, Sherman took his assigned target of Billy Goat Hill at the north end of the ridge, only to find that it was separated from the main spine by a rock-strewn ravine. When he attempted to attack the main spine at Tunnel Hill, his troops were repeatedly repelled by Patrick Cleburne's heavy division, the best unit in Bragg's army. Grant then ordered George Henry Thomas to attack at the center of the Confederate line. This frontal assault was intended as a diversion, but it unexpectedly succeeded in capturing the enemy's entrenchments and routing the Confederate Army of Tennessee, bringing the Union's Chattanooga campaign to a successful completion.