Febronianist reformer. Though he was only a subdeacon, in 1802 K. von Dalberg, Coadjutor Prince-Bishop of Constance, appointed him his vicar general. Besides initiating various reforms, he aimed at the creation of a National German Church, largely independent of the Papacy. At Rome his Josephinistic principles aroused opposition and Dalberg had to depose him. On Dalberg's death (1817) the Chapter elected Wessenberg as vicar and administrator of the diocese. In open disobedience to the Pope he acted as administrator until 1827, when the diocese of Constance was incorporated into that of Freiburg. He retired in 1833.