Around 858, the counts (or dukes, duces) Rihher of Pannonia and Pabo of Carinthia conspired against their overlord, the prefect Carloman.
This display of independence on Carloman's part startled his father, King Louis the German, into purging a party of noblemen who were close to Carloman (861) and granting extensive holdings in Pannonia and Carinthia to the Archdiocese of Salzburg (860).
Louis had secretly negotiated with Gundachar, however, and the latter went over with the army to the king's side in return for the appointment to Carinthia with the title of prefect.
While preparing to attack Carloman, he reportedly told his Moravian men that he Saint Emmeram of Regensburg, on whose relics he had sworn fealty to Louis, was holding his weapons down and preventing him from raising his arms and contributing to the fight.
He was killed in battle and Louis ordered celebrations to be made for his death.