*Caracalla, 211–217 A. D.* The bitter enmity which had long existed between the two brothers continued during a year of joint rule, and divided the empire into rival factions. Then Caracalla, who had previously sought to make himself sole ruler, succeeded in having Geta assassinated. Many of the latter’s friends, among them the prefect Papinian, were executed. Caracalla was cruel and vicious, and displayed no capacity for governing. He relied solely upon the goodwill of the soldiery and courted their support by increased pay and lavish donatives. In 212 A. D., by the famous Antonian Constitution (_constitutio Antoniniana_) he extended Roman citizenship to all the provincials of the empire, except those who were in a condition of vassalage, such as some of the barbarian peoples who had been settled on waste lands within the Roman borders, and not citizens of organized municipalities (_dediticii_). This act was the logical culmination of the policy of his predecessors who had granted citizenship to many provincial municipalities and had sanctioned its automatic extension to soldiers of the legions and auxiliary corps. Perhaps Caracalla’s chief motive was to supply a fresh source of income for the treasury, which was sadly depleted by his extravagances, for he greatly increased the number of those liable to the five per cent inheritance tax which fell only upon Roman citizens. A second motive may well have been the desire to secure a uniformity of legal status and of municipal organization throughout the empire. *Germanic and Parthian wars.* In 213 A. D. an attack of a confederacy of German tribes, the Alamanni, upon the Raetian frontier was successfully repelled, and in the next year Caracalla set out for the East, where he planned to conduct a Parthian war in imitation of the conquests of his idol, Alexander the Great. In 215, the Parthian king, Vologases V, came to terms, but when he was dethroned by his brother, Artabanos V, who refused Caracalla’s request for the hand of his daughter, Caracalla prepared to invade Parthian territory. But before he embarked on his venture he was assassinated by the order of the praetorian prefect Marcus Opellius Macrinus, April, 217 A. D.