Philip’s entry into Cologne in 1207 had practically brought the German civil war to a close.

Philip had been loosed from the papal ban a month or two later, and in March 1208 it seems probable that a treaty had been concluded by which a nephew of the pope was to marry one of Philip's daughters and to receive the disputed dukedom of Tuscany.

Philip is preparing to crush the last flicker of the rebellion in Brunswick-Lüneburg when on June 21, 1208, he is murdered at Bamberg by Otto VIII of Wittelsbach, count palatine in Bavaria.

Otto, already known for his unstable character, had fallen into a rage when he learned of the dissolution of his betrothal to Gertrude of Silesia by her father, Duke Henry I the Bearded of Lower Silesia.

Henry, apparently informed of the Wittelsbach's cruel tendencies, had in an act of concern for his young daughter decided to terminate the marriage agreement.

Otto proceeded to blame Philip, without grounds, for another spurned marriage alliance (the first being to Philip's own daughter, Beatrice) and had sworn revenge on the German King, culminating in the murder at Bamberg.