The pro-Union counties of eastern Tennessee offered little resistance to the occupation of Knoxville by forces under Maj. Gen. Ambrose E. Burnside in 1863. As a Confederate army besieged Union forces at Chattanooga, Tennessee later that year, a force under the command of Lt. Gen. James Longstreet was sent to Knoxville to prevent Burnside's Army of the Ohio from moving in support of Chattanooga. To capture Knoxville, Longstreet decided that Fort Sanders, located northwest of the city, was the only vulnerable place where his men could penetrate Burnside’s fortifications. Longstreet believed he could assemble a storming party, undetected at night, and, before dawn, overwhelm the fort. On November 29th, following a brief artillery barrage directed at the fort’s interior, three Rebel brigades charged forward. Union telegraph wire entanglements delayed the attack, but the fort’s deep outer ditch halted the Confederates. Crossing the ditch was nearly impossible, especially under withering defensive fire from musketry and canister. Confederate officers led their men into the ditch, but, without scaling ladders, few emerged on the other side. A small number entered the fort to be wounded, killed, or captured. The Confederate defeat at Knoxville, plus the loss of Chattanooga four days earlier, put most of eastern Tennessee in Union control for the rest of the war.