As Burnside was fortifying Knoxville, the Confederate army defeated the Union forces at the Battle of Chickamauga (near the Tennessee-Georgia line) and laid siege to Chattanooga. On November 3, 1863, the Confederates sent General James Longstreet to attack Burnside at Knoxville. Longstreet wanted to attack the city from the south, but lacking the necessary pontoon bridges, he was forced to cross the river further downstream at Loudon (November 14) and march against the city's heavily fortified western section. On November 15, General Joseph Wheeler unsuccessfully attempted to dislodge Union forces in the heights of South Knoxville, and the following day Longstreet failed to cut off retreating Union forces at Campbell's Station (now Farragut). On November 18, Union General William P. Sanders was mortally wounded while conducting delaying maneuvers west of Knoxville, and Fort Loudon was renamed Fort Sanders in his honor. On November 29, following a two-week siege, the Confederates attacked Fort Sanders, but failed after a fierce 20-minute engagement. On December 4, after word of the Confederate setback at Chattanooga reached Longstreet, he abandoned his attempts to capture Knoxville and went into winter quarters at Russellville. He rejoined the Army of Northern Virginia the following Spring.