For the first time since the end of the Merovingian dynasty a king had been murdered. Besides Albert I of Habsburg (1308), Philip is the only Roman-German ruler to be assassinated. No chronicler witnessed the murder. In contemporary sources there is little agreement about the course of the murder. Most medieval chroniclers saw the withdrawal of the promise of marriage as a motive for murder. Even in distant Piacenza, Philip's murder was still associated with a failed marriage project. Allegedly the Wittelsbach scion, 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, the Piast Duke Henry I the Bearded, who was apparently informed of Count Otto VIII's cruel tendencies and in an act of concern for his young daughter decided to terminate the marriage agreement. Later, after an unfortunate campaign to Thuringia, Philipp had betrothed his third daughter Kunigunde to Count Otto VIII in the summer of 1203 in order to make him a reliable ally in the fight against Landgrave Hermann I of Thuringia. In the following years Philip increasingly succeeded in gaining acceptance for his kingship, so the betrothal with the Wittelsbach became without purpose to him; in November 1207 the King engaged Kunigunde to Wenceslaus, son and heir of King Ottokar I of Bohemia, on the "Hoftag" in Augsburg. Philipp hoped that this alliance would gain permanent support from Bohemia. For Count Otto VIII this behavior was an act of treason and also felt that his social status was threatened; he swore revenge on the German King, whom he blame for both spurned betrothals, culminating in the murder at Bamberg.