During the autumn of 1863, Union General Ambrose E. Burnside's forces occupied Knoxville and much of the surrounding countryside, with Philadelphia, a station on the East Tennessee and Georgia Railroad, serving as the southernmost Union-held town. Colonel Frank Wolford's brigade, including the 1st, 11th, and 12th Kentucky Cavalry Regiments, the 45th Mounted Infantry, and six mountain howitzers, occupied Philadelphia and protected the railroad. On October 20, 1863, two Confederate cavalry brigades approached the town as Colonel George Dibrell advanced from the south and Colonel John J. Morrison moved in from the west, with Dibrell meant to distract the Federals while Morrison attacked from the north. Unaware of these movements, Wolford had sent wagons westward for supplies, and Morrison's men captured them, sent them south, and continued their advance. Hearing firing to the west, Wolford realized a fight had begun and dispatched almost half his troops to recover the wagons. Morrison's assault on the Union position, which local tradition places on Federal Hill, succeeded, and Wolford fought in two directions until, after learning that his mountain howitzers were nearly out of ammunition, he ordered a retreat when the last round was fired. His men fled to Loudon, leaving behind the guns. The battle marked the first defeat of Union forces during the occupation of East Tennessee. Adjutant General George W. Brent reported that Colonels Dibrell and Morrison captured 700 prisoners, 50 wagons loaded with stores, 6 pieces of artillery, 10 ambulances, and many horses, mules, and other property. The mountain howitzer was a short-barreled, large-caliber cannon built on a small scale so pack animals could carry it, making it well suited for fast-moving cavalry because it could go wherever horses and mules could go and was light enough for soldiers to move by hand during a fight.