 Complete the following phrase:  The 15th Texas Cavalry Regiment was a unit of cavalry volunteers mustered into the Confederate States Army in March 1862 and fought during the American Civil War. In July 1862 the unit was dismounted and served the remainder of the war as infantry. The regiment was captured at Arkansas Post in January 1863. After being exchanged three months later, the much-reduced 15th Texas was consolidated with two other regiments and assigned to Patrick Cleburnes division in the Army of Tennessee. The consolidated regiment fought at Chickamauga, 