 According to feudal law, the immediate heritable fees fell back to the suzerain, the Holy Roman Emperor.However, Emperor Frederick II, in the last years of his rule, was weakened by the struggle against Pope Innocent IV, and was stuck in the Italian Wars between the Guelphs and Ghibellines.His death in 1250 and the death of his only surviving son King Conrad IV four years later ended the line of Hohenstaufen rulers, only eight years after the extinction of the Babenberg dynasty.