For more than 200 years the Empire was governed monarchically, first by the Julio-Claudians, then, after a short interval of civil war, by the Flavians. Both these houses were determined to establish and maintain a hereditary dynasty, based on direct lineal descent. The only emperors who did not come to power in this way were Augustus, Otho, Vitellius, and Vespasian, who acquired it by force of arms, and Galba, who was elected by the Senate.