In Austrasia, the mayoral office became hereditary in the family of the Pippinids. In 687, after victory over the western kingdom of Neustria, the Austrasian mayor, Pippin of Herstal, took the title Duke of the Franks to signify his augmented rule. His son and successor, Charles Martel, ceased bothering with the façade of a king, and the last four years of his reign (743–47) were an interregnum, after which the Pippinids assumed the title and power of a king themselves.