In 1244 Heinrich von Hohenlohe was appointed Grand Master of the Teutonic Order (Hochmeister des Deutschen Ordens). His careen in the Order is closely linked with the rich donation he made to the newly founded Order together with his brothers Andreas and Friedrich in 1219. At that time the family's water-surrounded castle with its landholdings around Mergentheim were transferred to the possession of the Teutonic Order. The brothers, who came from a very wealthy Franconian noble family, had become members of the Order after taking part in a Crusade..
Between 1732 and 1761 Clemens August, the younger brother of Elector Karl Albrecht von Bayern (later Emperor Karl VII), was Grand Master in the Mergentheim residential palace. Before that he acted as Bishop of Münster and Paderborn, and, in addition to his title of Grand Master, also held the title of Elector of Cologne and Bishop of Hildesheim and Osnabrück. During his time as Grand Master the new Palace Church (Schlosskirche) and additional baroque structural alterations to the palace were completed.
Duke Paul von Württemberg received Mergentheim Palace as his residence in 1827 following his marriage to Princess Sophie Dorothee Caroline von Thurn und Taxis. During his numerous travels in Europe and abroad he completed his ethnographic collections, which he kept at the palace. He was one of the most important naturalists of the 19th century. A fraction of his collection still exists and is kept at the "Lindenmuseum" in Stuttgart. Duke Paul died on 11/26/1860 in Mergentheim and is buried in the Cathedral (Stiftskirche) in Stuttgart.
Although the poet Eduard Mörike never lived at Mergentheim Palace, he did visit the collections of Duke Paul von Württemberg there several times during his stay in town (1845-1851). In the collection on town history his housekeeping book from this time is still on exhibit today. It contains a large number of drawings and miniatures on the subject of life in Mergentheim.