Let me do some quick research and I will give you what I find.

A.C. McDonald may have served with Col.William Steele from 1861 until 1863 and could have went with Steele tohis new assignment at Galveston. Col. William Steele was in command of the 7th Texas Cavalry during Brig. Gen. H.H. Sibley's New Mexico Campaign and was briefly in command of operations in Indian Territory at Boggy Depot. In 1863, Steele was replaced by Maj.Gen. Samuel B. Maxey and Gen. Steele took command of artillery at Galveston.

Also Brig. Gen. Smith P.Bankhead was in command of the 14th Brigade, Texas State Troops in Bonham, Texas. Before coming to Texas, he was a captain of artillery and distinguished himself at Shiloh. On August 23, 1863, he left Bonham and was transferred to Galveston with Gen. Steele and took command a battery of artillery, a branch of the service he knew something about.