Karlsruhe, a city in Germany (Karlsruhe was formerly Carlsruhe)
Duke William was born at Carlsruhe, Kingdom of Prussia (now Pokój, Poland) was the first child of Duke Eugen of Württemberg (1788–1857), (son of Duke Eugen of Württemberg, and Princess Louise of Stolberg-Gedern) by his second marriage to Princess Helene of Hohenlohe-Langenburg (1807–1880), (daughter of Charles Louis, Prince of Hohenlohe-Langenburg and Countess Amalie of Solms-Baruth).