Louis was hastily crowned German King of the Romans by Peter in Aachen, while Frederick was crowned in Bonn by the Prince-Elector of Cologne. A bloody conflict broke out between the two kings and lasted for years, while Pope John XXII tried to stay neutral in the first years. Finally, Frederick was decisively defeated in the Battle of Mühldorf in 1322. Louis IV became Holy Roman Emperor in 1328. Peter von Aspelt, however, did not live long enough to witness this. He had already died in 1320. Matthias von Buchegg succeeded him as Archbishop of Mainz in 1321.