The Severan dynasty comprised the relatively short reigns of Septimius Severus (r. 193211 A.D.), Caracalla (r. 21117 A.D.), Macrinus (r. 21718 A.D.), Elagabalus (r. 21822 A.D.), and Alexander Severus (r. 22235 A.D.). Its founder, Septimius Severus, was a member of a leading native family of Leptis Magna in North Africa who allied himself with a prominent Syrian family by his marriage to Julia Domna. Their union, which gave rise to the imperial candidates of Syrian background, Elagabalus and Alexander Severus, testified to the broad political franchise and economic development of the Roman empire. It was Septimius Severus who erected the famous triumphal arch in the Roman Forum, an important vehicle of political propaganda that proclaimed the legitimacy of the Severan dynasty and celebrated the emperor's victories against Parthia in a lavishly sculpted historical narrative. As in most artistic achievements under the Severans, the monumental reliefs show a decisive break with classicism that presaged Late Antique and Byzantine works of art. At Leptis Magna, he renovated and embellished a number of monuments and built a grandiose new temple-forum-basilica complex on an unparalleled scale that befitted the birthplace of the new emperor. Septimius cultivated the army with substantial remuneration for total loyalty to the emperor and substituted equestrian officers for senators in key administrative positions. In this way, he successfully broadened the power of the imperial administration throughout the empire. By abolishing the regular standing jury courts of Republican times, he was likewise able to transfer power to the executive branch of the government.
His son, Marcus Aurelius Antoninus, nicknamed Caracalla, obliterated all distinctions between Italians and provincials, and enacted the Constitutio Antoniniana in 212 A.D., which extended Roman citizenship to all free inhabitants of the empire. Caracalla was also responsible for erecting the famous baths in Rome that bear his name. Their design served as an architectural model for later monumental public buildings. He was assassinated in 217 A.D. by Macrinus, who then became the first emperor who was not a senator. The imperial court, however, was dominated by formidable women who arranged the succession of Elagabalus in 218 A.D., and Alexander Severus, the last of the line, in 222 A.D. In the last phase of the Severan principate, the power of the Senate was finally revived and a number of fiscal reforms were enacted. The fatal flaw of its last emperor, however, was his failure to control the army, eventually leading to mutiny and his assassination. The death of Alexander Severus signaled the age of the soldier-emperors and almost a half-century of civil war and strife.