The 13th Infantry Regiment ("First at Vicksburg") is a United States Armyinfantry regiment whose battalions are currently tasked as basic training battalions.

During the first post-war expansion of the United States Army following independence, a 13th Regiment of Infantry was formed on 16 July 1798, and was mustered out 11 January 1800. The second 13th Infantry was constituted 11 January 1812. Following the War of 1812 the 13th Infantry was consolidated on 7 May 1815, with the 4th, 9th, 21st, 40th, and 46th Regiments into a new 5th Infantry Regiment whose lineage continues to the present.