After the Battle of Chickamauga in September 1863, Union Gen. William S. Rosecrans retreated to Federal-occupied Chattanooga, a strategically vital rail center, where Confederate Gen. Braxton Bragg laid siege from Lookout Mountain and Missionary Ridge. Union Gen. Ulysses S. Grant took command in October and began efforts to break the siege, while Bragg detached forces under Gen. James Longstreet to attack Knoxville as a diversion. After Gen. William T. Sherman reinforced Grant in November, the Federals attacked the heights and Bragg retreated, and the Union army held the city for the rest of the war. During the early days of the siege, the Union army's only supply route followed a long and difficult road from Bridgeport, Alabama, north up the Sequatchie Valley and then east over Walden's Ridge on the Anderson Pike before descending just north of here and running along the Tennessee River to Chattanooga. On October 8, the 4th Alabama Volunteer Infantry took position along the bluffs of the Tennessee River on Raccoon Mountain across the river and acted as sharpshooters, firing at the mules of Union wagon trains forced to pass along the narrow road between the bluff and the river. This compelled the wagons to detour north and descend the mountain along a partially planked road into Hamilton Valley, a route described by a Union officer as rickety, insecure, makeshift, and so narrow that only in places could two teams pass each other. By October, supplies barely trickled into besieged Chattanooga and starvation seemed possible, but late in the month Union forces seized Brown's Ferry and opened an easier supply route through Lookout Valley. Wagons then rolled into Chattanooga along the safer Cracker Line, named for wagonloads of hardtack, and the city's supply situation became less dire.