Donna,
There are only 2 cards for him in compiled records of 18th Tex. Cav.

1. Company Muster-in Roll; Capt Milton Wesley Damron's Company, Darnell's Regiment Volunteers, (became Co.D 18th Tex.
Cav.)

Pvt. Joel Blackwell, age 40, Mustered in March 15,1862 at Dallas, Dallas Co, Texas. Enlisted Bell County,Texas no dated, for 1 year.
Value of horse $125.00 and equipment $30.00.

2. Muster Roll; Jun 15-Jun 30 1862, Pvt. Joel Blackwell, Co. D, 18th Tex Cav. Enlisted Jan 15'1862 at Belton, Texas, for 1 year, by M.W. Damron, not paid, Present.

Note: This company was at Arkansas Post when it was surrendered on Jan. 11,1863, and only 6 men escaped. 2Lt. John Brown and 5 enlisted men, also Capt Damron was on furlough at the time. Most records where lost or destoryed.

Mike