William's father was Jacob Thomas of Rowan County, North Carolina, also a Revolutionary War soldier, who married Margaret Brevard.
David Thomas's mother Elizabeth was the daughter of American Revolutionary War soldier John Purviance of Rowan County, who married Mary Jane Wasson.
His writings in the Texas State Archives as Secretary of War reveal, by the degree of shakiness of handwriting, the relative proximity to the Texans of Santa Anna's troops heading toward San Jacinto.
David Thomas is buried in a hero's grave in the de Zavala Cemetery in the San Jacinto battlefield state shrine near Houston.
One of them was David E. Thomas, by then an attorney in Austin, Texas, who responded to an inquiry from McCorkle that the land grant was not worth claiming, for it was subject to Indian depredations and back taxes amounting to more than its fair market value.