I could not find Hamilton Wiley Blackwell in the NPS Soldiers and Sailors System.

However, here is a brief history of his unit. The 13th Texas Cavalry (13th Texas Mounted Volunteers) was mustered into the Confederate army and 900 recruits underwent training from September 1861 until January 1862 at Crockett, Texas. Col. John H. Burnett took command of the regiment in February 1862 and was assigned to Gen. John G.Walker's Texas Divison where the regiment saw action at Jenkin's Ferry on April 30, 1864.

The 13th Texas Mounted Volunteers should not be confused with Lt. Col. Edwin Waller's 13th Texas Cavalry Battalion. Lt. Col. Waller was promoted to colonel in December 1864 and was placed in command of the redesignated 13th Texas Cavalry Regiment.