Middle Roman Empire, Non-dynastic (217-218): Macrinus, Diadumenian

24 *MACRINUS (c.53; r.217-218)

25 *DIADUMENIAN (9; r.218)

Macrinus was born in Mauretania. He earned a reputation as a jurist in Rome, becoming a legal adviser to the praetorian prefect Plautianus and a financial adviser of Severus’ private estates. He was appointed praetorian prefect in 212 and was taken by Caracalla on his campaign against Parthia in 216.

He now sent a letter informing the Senate of his actions and anticipating their reply he assumed the prerogatives of office and appointed his eight-year-old son Opellius (02) Diadumenianus (9; fl.217-218) as caesar. Knowing the importance of dynastic continuity as a source of legitimacy Macrinus added ‘Severus’ to own name and ‘Antoninus’ to his son’s. 

Macrinus complained to the Senate about the cost of Caracalla’s pay rise to the army (which cost seventy million denarii annually) and rescinded it, at least for new recruits. Not surprisingly, he was unable to retain the loyalty of the army.

It was essential for him to end the war and return to Rome as quickly as possible in order to secure his claim. On Caracalla’s death, Tiridates II (r.217-252) was declared king of Armenia and the province was allowed to pass out of Roman control. In the summer Artabanus V outflanked the Roman army and attacked its rear in northern Mesopotamia. The two armies met in a major but inconclusive battle at Nisibis. In early spring the Romans agreed a peace treaty in which they agreed to pay an indemnity of fifty million denarii to Parthia.

⁰⁹Julia Domna’s sister, ¹⁰Julia Maesa (61; fl.217-226), was married to the Syrian nobleman ³¹Julius Avitus (c.62; fl.194-217), and they had two daughters: ¹¹Julia Soaemias (42; fl.217-222), mother of ⁰⁴Varius Avitus Bassianus (the future emperor Elagabalus); and ¹²Julia Avita Mamaea (45; fl.217-235), mother of ³⁶Julius Gessius Bassianus (the future emperor Severus Alexander).

While it was clear that ¹⁰Julia Maesa and her powerful relations in Syria posed a dangerous threat to Macrinus’ rule, he could not while proclaiming his innocence with regard to Caracalla’s death, sensibly take any action against them that would seem disloyal to his memory. Macrinus therefore merely ordered ¹⁰Julia Maesa to leave Antioch and return to her family home at Emesa (=Homs, west Syria), but made the crucial mistake of leaving her family’s fortune intact.

Knowing how the army cherished the memory of Caracalla, Maesa concocted the rumour that Elagabalus was his illegitimate son and therefore a real Severus. On 16 May 218 he was presented to Legio III Gallica at Raphanae (north Jordan). After the offer of a large donative and with the connivance of the commander of the legion Valerius (21) Comazon (fl.218-220+), they saluted him as augustus under his royal name, that of his fictive father, Marcus ⁰⁸Aurelius Antoninus.

When news of this reached Macrinus at Antioch, he sent a force under the praetorian prefect ⁰⁴Ulpius Julianus to put down the revolt at Emesa. In the meantime, Macrinus proceeded to Apamea (northwest Syria), where he raised his son to augustus and gave the praetorians a generous bonus. At Emesa Julianus’ men deserted and the severed head of Ulpius Julianus was delivered to Macrinus at Antioch.

On 8 June, Elagabalus’ tutor Gannys inflicted a decisive defeat on Macrinus’ army at Immae, about twenty miles from Antioch. Macrinus and his son Diadumenian were captured while attempting to flee and put to death.