He moved to Chattanooga in 1850 and established Grenville Flour Mill, located along Chestnut Street near the intersection of Ninth Street, at the back of the present day Read House.  Grenville’s mill was one of Chattanooga’s largest industries prior to the Civil War.

He had faith in Chattanooga and accumulated considerable amount of property, but lost his fortune during the American Civil War. Grenville Flour Mill was destroyed during the War, and it is said that it frequently served as a target when Chattanooga was shelled by Union forces. All of his properties were virtually destroyed.

Mayor Grenville married February 27, 1851 to Margaret MacMurphey, daughter of a pioneer settler of Augusta, Georgia.  They had three children, only one survived, Mrs. Mary Grenville Mullings of Atlanta, Georgia.