In 916 Conrad's forces invaded Bavaria, attacking and pillaging Regensburg. These attacks drove Arnulf into exile with his former enemies in Hungary. In September, the king convoked a church council in Hohenaltheim, attended by the Bavarian episcopate, which summoned Arnulf and his younger brother Berthold on the grounds of excommunication at Regensburg on 1 November. It is more than likely that Arnulf and his family never appeared at the convocation, or that the council meeting was never held. As a result, they remained exiled among the Hungarians. In January 917, King Conrad, angered at the situation, called for the execution of his rebellious Swabian brother-in-law, Erchanger and his brother Berthold, giving Arnulf more pause for concern.