The siege of Knoxville (November 19 – December 4, 1863) saw Lieutenant General James Longstreet's Confederate forces besiege the Union garrison of Knoxville, Tennessee, led by Major General Ambrose Burnside. When Major General William T. Sherman approached Knoxville with an overwhelming Union force, Longstreet ended the siege on December 4 and withdrew northeast. The siege was part of the Knoxville campaign of the American Civil War. In August and September 1863, Burnside's Army of Ohio carried out a nearly bloodless invasion of East Tennessee, an area that included a substantial pro-Union population. Burnside's occupying force was thrown on the defensive when Longstreet's corps and Major General Joseph Wheeler's cavalry launched a counter-invasion from the southwest in November. Longstreet missed his chance to smash the Union forces in the field when Burnside conducted a successful fighting withdrawal to Knoxville. When Longstreet hesitated to attack, the Union soldiers built fortifications to make Knoxville's strong natural defenses even more powerful. Longstreet's forces lacked sufficient strength to completely surround Knoxville. Therefore, Burnside's Union garrison avoided starvation by bringing food into the city from the south bank of the Tennessee River. On November 29, a major Confederate assault was repulsed with heavy losses in the Battle of Fort Sanders. Aside from day-to-day skirmishing, there were two other significant actions, the first on November 18 west of the city and the second on November 25 at Armstrong's Hill on the south bank. After the siege ended, Longstreet's troops lingered in East Tennessee until April 1864, but were unable to capture Knoxville. Background Union occupation Burnside, commanding the Union Army of the Ohio, mounted the Union invasion of East Tennessee in late August 1863, with two infantry divisions and one large cavalry division from XXIII Corps soldiers stationed in Kentucky. Burnside's offensive was mostly unopposed and Federal troops occupied Knoxville on September 1. Many of the people of East Tennessee were pro-Union and welcomed the Union troops. By mid-September, Burnside's troops had seized control over a large part of East Tennessee. When Bragg's Army of Tennessee defeated the Union Army of the Cumberland at the Battle of Chickamauga on September 19–20, 1863 the strategic situation dramatically changed. After his victory, Bragg effectively blockaded the Army of the Cumberland within Chattanooga. On September 20, two divisions of IX Corps joined Burnside, and on October 3, Brigadier General Orlando B. Willcox with 3,000 6-month Indiana soldiers arrived at Cumberland