ウラッハ公
Wilhelm married Elisabeth Theurer om 19 June 1928, in the teeth of opposition from his father. Elisabeth was the daughter of Richard Theurer, General Director of , a long-established Stuttgart manufacturer of dyes and colourings, and his wife Elizabeth, born Elisabeth Groß. By the date of his marriage, Wilhelm's father had been dead for nearly three months, but the marriage was nonetheless deemed morganatic, and he was required to renounce his right to the title Duke of Urach, Count of Württemberg. Headship of the noble family instead passed to his younger brother, Karl Gero, Duke of Urach.