Wheeler had marched back along the left bank of the Holston half-way to Lenoir's and crossed at Louisville, joining Longstreet again near Knoxville on the 17th, as has been already stated. He now took the advance and pressed sharply in upon the town. General Sanders had been recalled by Burnside from the south, and entering Knoxville by the pontoon bridge, passed out to the westward on the Loudon road, meeting the enemy as he advanced, and gradually falling back to a position a mile beyond the lines, where he made a stubborn stand and held Wheeler at bay till night closed the combat. From the fortified points about the city the cavalry engagement had been in full view, and the heroism of Sanders and his men was in the presence of a cloud of witnesses. They made little barricades of rail piles, and though these were frequently sent flying by the cannon balls and shells with which Alexander's artillery pounded them all day, they held at nightfall the line Sanders had been directed to hold in the morning, and had not given back an inch. [Footnote: Colonel O. M. Poe, in "Century War Book," vol. iii. p. 737.] Knoxville was so situated that its outline was a sort of parallelogram of high ground, averaging a hundred and fifty feet or more above the river which ran along the town on the south. Two creeks ran through the town in little valleys, and in the northern suburbs where the land was much lower than the town it had been practicable, by damming these streams to make inundations which covered a considerable part of the northern front and added very materially to the defences. At the four corners of the parallelogram, enclosed works had been planned for use by a small garrison, and these had been partly constructed. Captain Poe, the chief engineer, had staked out infantry lines connecting these forts, with epaulements for artillery at intervals, and work had been hastened during the days from the 13th of November, as soon as Burnside's plan of holding the city had been approved. When the troops approached the city on the morning of the 17th, the position for every brigade and every battery had been assigned, and officers were in waiting to lead each to its place. All the infantry was put in line except Reilly's brigade of the Twenty-third Corps, which was placed in reserve in the streets of the town. [Footnote: Poe's Report, Official Records, vol. xxxi. pt. i. p. 295.]