In 1777, Joseph's hasty military action led to the War of the Bavarian Succession. When the Austrian position became untenable, Kaunitz carried the peace negotiations on his own initiative; by the 1779 Treaty of Teschen, he won the Bavarian Innviertel region for Austria. In Imperial matters, he was able to dominate the Perpetual Diet of Regensburg; in 1780 he was also successful in placing the Habsburg Archduke Maximilian Francis of Austria, Joseph's younger brother, as a coadjutor bishop in the Electorate of Cologne and the Prince-Bishopric of Münster.