It is impossible to consider the background or history of Diadumenian without understanding the position of his father, Macrinus. In the great history of the Roman Empire, Diadumenian was a very minor figure and contributed nothing of importance to the annals of that long and illustrious chain of rulers. However, his issue of Greek Imperial coinage is impressive, particularly that of Moesia Inferior where the volume of types is prodigious but his image was used extensively throughout Asia Minor to bolster the impression that the line of succession was secure. Imperial coins of these two rulers are widely available – those of Diadumenian being somewhat scarcer – with the output being in line with that of an Emperor in place for approximately a year.

Cassius Dio provides most of the available detail of both Macrinus and Diadumenian’s life and while the Augusta Historia also records details of Diadumenian it is extremely unreliable and largely ignored here, being prone to hyperbole for this particular time. Macrinus was born in Caesarea, in the Roman province of Mauretania (modern day Morocco) and was of Moorish decent. Over the course of his young adulthood he trained, and was successful, as a lawyer and from there rose in the service of Septimus Severus. When Caracalla came to power in xxx, Macrinus was made a praetorian prefect, an equestrian post that was second only to the emperor in power. There were rumours that Macrinus was seeking to usurp Caracalla– which may or may not have been true – but even rumours had weight and Macrinus was forced to act before the rather paranoid Caracalla could dispose of him.

When campaigning in the east, Caracalla took time to visit the temple of Luna, some say he only left the main body of troops to urinate, and it was from there that a group of guards returned to the camp with Caracalla’s body and a dead soldier; their story being that the guard had committed the murder and had been killed during the subsequent fight. This story probably fooled no-one, but Macrinus had enough power to establish himself as the first ever Roman emperor who had not previously been a senator or had come from a senatorial family. Macrinus was proclaimed Emperor on 11th April 217.

Throughout his tenure as emperor, Macrinus seems to have avoided war wherever possible. He also lost a battle with the historically weaker enemy, the Parthians (under Artabanus V), and was forced to pay some 200 million sesterces in reparations. These acts coupled with the introduction of a new soldiers pay system where recruits were paid less than veterans caused discontent among the legions. Back in Rome (a city he never visited as emperor) natural disasters were poorly managed and the population were less than satisfied with him.

In the background to this discontent were the vestiges of the Septimus Severus dynasty, which were plotting to regain power using the teenager Bassinius (better known as Elagabalus) as a figurehead. Although Julia Domna had recently died, her sister, Julia Maesa accompanied by her daughters Julia Soaemias and Julia Mamaea managed to convince the eastern legion (II Parthica) to accept Elagabalus as the true successor to Caracalla (likely as his illegitimate son). Macrinus sent letters to the Senate proclaiming the Elagabalus as a pretender, insane and an enemy of Rome and both consuls, and other high ranking officials agreed with him. However, that alone was not sufficient avoid a confrontation with the forces of Elagabalus and so end of the brief interlude from Severn rule.

Diadumenian (Marcus Opellius Antoninus Diadumenianus) was the son of Macrinus (and probably Nonia Celsa) and was born on September 14th or 19th 208AD. There is no record of where he was actually born. He was only nine years old when Macrinus became Emperor and he was additionally named Caesar, and as part of the political manoeuvring, Diadumenian was given the name “Antoninus” – Caracalla’s name - hence on much of the provincial coinage attributed to him he is referred to as Marcus Opellius Antoninus Diadumenianus or some appropriate derivative. The likely date for his investiture as Caesar by the Senate is early May 217, though he may have been hailed as such by the soldiers at Zeugma in mid to late April of that year. Common practice names him Diadumenian rather than Diadumenianus and that convention is retained here unless it relates to a legend.

The portraits from the various provincial mints vary considerably, from showing a very young child (e.g. Tripolis) to more mature young adult suitable for rule (e.g., Cibyra). The Moesia Inferior mints in particular show a maturing of the portrait over time, but as he was Caesar for only a year, this is a political change of features rather than a true reflection of physical maturing. It is also interesting that some mints continually reflect very young features while others go down the more mature portraiture route, typical to their indigenous style.

Diadumenian was created Augustus and co-sovereign with Macrinus in 218, probably just prior to his battle with the forces of Elagabalus. Some imperial coins referencing him as Augustus do exist but they are exceedingly rare.

It is probable that Diadumenian would have accompanied his father closely on any travels during that fourteen month rule, given that he was the only link for succession. Unfortunately, no knowledge of where his family were based during this period has been preserved, though it was almost certainly somewhere in Asia Minor.

Macrinus lost the battle with the forces of Elagabalus on the 8th June and fled towards Rome where he was captured at Calchedon, (opposite Byzantium). While being transported back to Antioch he was executed. Diadumenian’s end came near Zeugma (coincidently near to where he was first elevated) as he was fleeing to refuge with Artabanus, king of the Parthians.

The coinage of Diadumenian show a wide variation considering both how young he was and that his father had only recently usurped power from the ruling dynasty. Some mints appear to have ceased working during the Macrinus and Diadumenian period while the output of others (mostly of the larger cities) continued unabated. The range of types is notable in that they do not slavishly follow that of his father, though there is a good degree of overlap.

Roman Provincial coinage in itself is very diverse and designs and types follow local traditions and styles. The vast majority of mints were situated in Asia Minor (modern day Turkey) or around the Danube basin, although those operating in the Levante or Egypt also fall within the ‘provincial’ sphere.

The large mint of Nikopolis ad Istrum in Moesia Inferior had a prodigious output of types frequently re-using obverse and reverse dies and it is not uncommon to find the same reverse die used for separate father and son issues.

The neighboring mint of Markianopolis, similarly shared obverse dies (with different local reverse dies), most notably for the 5 assaria pieces, though the presentation of dual portraits are complicated by the reversing of the order in which they are shown, where sometimes Diadumenian is shown on the left (facing right), an arrangement normally reserved for the senior emperor. This is not an indication of Diadumenian’s elevation to Augustus as the named governor on these pieces is usually Pontianus, and Diadumenian’s elevation only took place during the governorship of Agrippa.

The output of Diadumenian issues in Deultum (Thrace) was also significant with a wide variety of reverse types typical to the city. Antioch (Syria) also issued considerable coinage for the Caesar as this was the main city to the east of the Empire.

Most of the other provincial mints issuing coins for Diadumenian limited the number of types to less than a dozen. Even so, the range and quality of the outputs rival that of many of the established and long-serving Emperors. Indeed the koinon of Macedonians (neokoroi) first issued for Diadumenian indicating a degree of innovation here at this time.

A study of the types associated with this ruler give a flavour of the diversity seen in the issue of Roman Provincial coins without the depth needed to fully understand any particular city or mint. What it does show, however, is that within the space of a year the image of an unknown child, thrust into the limelight by the actions of his father, was circulated and adapted to suit the needs of many civic authorities. From the wine producing regions of the edge of the Black Sea to the deserts of the Levant, they saw the necessity or advantage of producing local coinage bearing his image, likely anticipating a long Macrinus rule. When placing the coins in the context of their own mints they are (with few exceptions) of excellent quality with skilled engravors employed in issuing high quality examples.