Macrinus, after three days' interregnum, being elected emperor, began his reign by purchasing a peace from the Parthians. What the empire chiefly needed at this moment, is evident from the next step taken by this emperor. He labored to restore the ancient discipline of the armies in all its rigor. He was aware of the risk he ran in this attempt; and that he _was_ so, is the best evidence of the strong necessity which existed for reform. Perhaps, however, he might have surmounted his difficulties and dangers, had he met with no competitor round whose person the military malcontents could rally. But such a competitor soon arose; and, to the astonishment of all the world, in the person of a Syrian. The Emperor Severus, on losing his first wife, had resolved to strengthen the pretensions of his family by a second marriage with some lady having a regal "genesis," that is, whose horoscope promised a regal destiny. Julia Domna, a native of Syria, offered him this dowry, and she became the mother of Geta. A sister of this Julia, called Moesa, had, through two different daughters, two grandsons--Heliogabalus and Alexander Severus. The mutineers of the army rallied round the first of these; a battle was fought; and Macrinus, with his son Diadumenianus, whom he had adopted to the succession, were captured and put to death. Heliogabalus succeeded, and reigned in the monstrous manner which has rendered his name infamous in history. In what way, however, he lost the affections of the army, has never been explained. His mother, Sooemias, the eldest daughter of Moesa, had represented herself as the concubine of Caracalla; and Heliogabalus, being thus accredited as the son of that emperor, whose memory was dear to the soldiery, had enjoyed the full benefit of that descent, nor can it be readily explained how he came to lose it.