I did find a reference to Speake that indicates he did attain a higher rank - but it looks like you are correct that he never commanded a company. This is from "Memorial Record of Alabama - 1893" vol ll, page 474, in reference to Judge Henry Clay Speake:
"He entered the Confederate army in August 1862, as a private in company D, Fourth Alabama regiment of cavalry, and was soon after promoted to sergeant-major, and later, to adjutant of the regiment. In January, 1864, he was appointed quartermaster of the regiment, and was captured with a part of Forrest’s command near Columbus, Ga."