DIEDENHOFEN (Fr. Thionville), a fortified town of Germany, in Alsace-Lorraine, dist. Lorraine, on the Mosel, 22 m. N. from Metz by rail. Pop. (1905) 6047. It is a railway junction of some consequence, with cultivation of vines, fruit and vegetables, brewing, tanning, &c. Diedenhofen is an ancient Frank town (Theudonevilla, Totonisvilla), in which imperial diets were held in the 8th century; was captured by Condé in 1643 and fortified by Vauban; capitulated to the Prussians, after a severe bombardment, on the 25th of November 1870.