Severan dynasty
In 217 - 218 there was a short interruption of dynasty's control over the empire by reigns of Macrinus (r. 217–218)[1]: 1292 and his son Diadumenian (r. 218) before Julia Domna's relatives assumed power by raising her two grandnephews, Elagabalus (r. 218–222)[1]: 212 and Severus Alexander (r. 222–235)[1]: 212 , in succession to the imperial office[1]: 1292 .
Although Septimius Severus restored peace following the upheaval of the late 2nd century, the dynasty's rule was disturbed by unstable family relationships and political instability, especially the rising power of the praetorian prefects[2]: 170 .
In April 9 145, Lucius Septimius Severus was born in Leptis Magna[3]: 1 , then in the Roman province of Africa Proconsularis and now in Libya, into a Libyan-punic family of equestrian rank[4]: 2-3 .
Severus was proclaimed emperor in 193 by his legionaries in Noricum[4]: 3 during the political unrest that followed the death of Commodus[3]: 97 , and secured sole rule over the empire in early 197, after defeating Clodius Albinus at the Battle of Lugdunum[3]: 125 [4]: 6 .
Later he raised a Macedonian phalanx to emulate Alexander the Great, and marched through Asia and Syria to Alexandria, inviting mockery of many whom he executed[1]: 212 .
After months of rebellion and a failed attack on the rebellious troops, Macrinus met the army of Elagabalus near Antioch where he was decisively defeated[4]: 21 [8]: 14 [1]: 1039 .
Macrinus managed to escape with his son to Chalcedon where he was apprehended to be taken back to Antioch, but the guards murdered him en route[4]: 21 .
Another account of the events tells how Elagabalus was being protected and raised by Gannys, a foster father and lover of his mother, Julia Soaemias[8]: 11 .
In this version of events, Gannys dressed young Elagabalus in Caracalla's childhood clothes and smuggled him into the camp at night, where soldiers eventually revolted the next morning[8]: 11 .
However, epigraphical and numismatic evidence shows that Elagabalus did replace Jupiter with Elagabal in late 220[8]: 18 , and he also married a Vestal Virgin called Aquilia Severa[1]: 212 .
In addition to these offences to Roman sensibilities, he was also accused of being murderous and bloodthirsty, but executions during his reign appear to be politically motivated instead of being the result of simple bloodlust[8]: 97 .
In 221, seeing that her grandson's outrageous behaviour could mean the loss of power, Julia Maesa persuaded or forced Elagabalus to adopt his cousin, Severus Alexander[1]: 212 , as caesar and his heir[8]: 37 .
At the same time he was forced divorce Aquilia in order to marry Annia Faustina, a relative of Marcus Aurelius, only to take Aquila back in a few months before the end of 221[1]: 212 .
The rising strength of the Sasanian Empire (r. 226–651) heralded perhaps the greatest external challenge that Rome faced in the 3rd century; however, in 231 Alexander organised an expedition to Parthia, nominally leading it, and by this did maintain control over the province of Mesopotamia[1]: 212 .
Alexander's reign ended in early 235 when he was murdered, together with his mother, by his own troops while he was wintering in Germany where he was in order to prosecute a war in Upper Germania[1]: 213 .
His successor was Maximinus Thrax (r. 235–238), the first in a series of weak emperors, which ended 50 years later with the Tetrarchy instituted in the reign of Diocletian (r. 284–305).
