Philip of Swabia (swāˈbēə) [key], 1176?–1208, German king (1198–1208), son of Holy Roman Emperor Frederick I. After the death (1197) of his brother, German King and Holy Roman Emperor Henry VI, he unsuccessfully attempted to secure the succession in Germany of his infant nephew, the later Holy Roman Emperor Frederick II; for the sake of the house of Hohenstaufen, he finally consented to his own election as German king. A small, anti-Hohenstaufen group led by the archbishop of Cologne elected (1198) Otto IV antiking. In the ensuing war Philip was supported by Philip II of France, while Otto had the support of his uncle Richard I of England. Though successful at first, Philip's cause was weakened when Pope Innocent III declared (1201) for Otto. However, the year 1204 marked a turn in Philip's favor; with his capture (1206) of Cologne, the war was virtually ended. Negotiations with the pope had resulted in a satisfactory settlement when Philip was murdered by a personal enemy. Otto IV was elected his successor as German king. Philip became involved in the Fourth Crusade (1202–4; see Crusades) partly through his marriage to the Byzantine princess Irene, daughter of Emperor Isaac II. The extent of Philip's influence in diverting the crusade to Constantinople is still debated.