Probus Billon Antoninianus, RIC V Probus 173

Monetary and Political Context

The antoninianus designated as RIC V Probus 173 was struck during the volatile period of the late third century, when the Roman Empire was recovering from decades of fragmentation, invasion, and fiscal instability. Following the murder of Aurelian and the brief reigns of Tacitus and Florianus in AD 276, Probus assumed the purple and continued the consolidation of the empire's frontiers. Crucial to this effort was the maintenance of the reformed monetary system introduced by Aurelian in AD 274. Aurelian had attempted to stabilize the deeply degraded antoninianus, establishing an alloy that contained approximately five percent silver, or one part silver to nineteen parts base metal, often indicated by the XXI mark on contemporary radiates. Under Probus, the mints sustained this reformed standard, striking substantial volumes of radiates to satisfy the financial requirements of continuous campaigns in Gaul, Illyricum, and the East. The issue represented by RIC 173 belongs to the output of the central imperial mint at Rome. It is situated within an ideological program that sought to project stability, legitimacy, and divine endorsement. In an era when military loyalty was precarious, invoking the supreme deity of the Roman pantheon served as vital political messaging for the sovereign.

Production Standards and Mint Organization

RIC V Probus 173 was produced exclusively at the mint of Rome. In this era, the urban mint operated with multiple officinae, or operational workshops, each identified by letters or numerical symbols in Greek or Latin alphabets within the coin's exergue or field. The mint utilized seasoned engravers who maintained a distinctive stylistic profile, characterized by compact bust proportions, precise rendering of military cuirasses, and clean, balanced letterforms. Metallurgically, although classified under the generic silver category in traditional numismatic catalogues, specimens belonging to RIC 173 were struck on billon planchets containing roughly 3.5 to 5 percent silver. The mint applied a chemical depletion-silvering technique, pickling the blanks in an organic acid bath prior to striking to dissolve base surface copper and leave a microscopically thin silver-enriched exterior layer. Weight standards across the series centered on an imperial target between 3.5 and 4.2 grams, with diameters commonly spanning 21 to 24 millimetres. Flans were cast in continuous molds or prepared from hammered strips, yielding irregular flan edges and typical minor striking cracks characteristic of high-volume late-Roman billon production.

Obverse Typology

The obverse of RIC V Probus 173 features a radiate, cuirassed bust of Probus turned to the right. The radiate crown, which visually denoted the denomination of the double denarius or antoninianus since its introduction under Caracalla in AD 215, is rendered with well-defined spikes radiating from a central band resting on the emperor's closely cropped hair. Probus is portrayed in martial dress, wearing a detailed cuirass fitted with shoulder straps and decorative pteryges visible beneath the mantle. His facial features are typical of the soldier-emperors from Illyricum: a square jaw, prominent brow, close-trimmed beard indicated by delicate stippling or hatching, and a determined gaze. Unlike many alternative obverse varieties of Probus that incorporate a consular mantle, shield, or raised spear, the portraiture of RIC 173 adheres strictly to the classic cuirassed bust without secondary weaponry, emphasizing straightforward imperial command.

Reverse Iconography and Theology

The reverse of RIC V Probus 173 is dedicated to Jupiter the Conservator, depicting the supreme deity standing in a frontal posture with his head turned left. Jupiter is shown nude or lightly draped with a cloak hanging over his shoulder, holding a thunderbolt in his right hand and a long vertical sceptre in his left hand. The iconographic construct of Jupiter Conservator, the preserver and protector of the emperor, held deep religious and political significance. In Roman state theology, Jupiter was the ultimate guarantor of imperial victory and cosmic order. By depicting Jupiter armed with the thunderbolt, the design directly linked the safety and authority of Probus to the omnipotence of Rome's greatest god. This theme reassured both the civilian populace and the legions that Probus ruled under celestial protection, a necessary reassurance during a reign troubled by repeated usurpers and relentless frontier incursions.

Inscriptions and Epigraphy

The obverse legend for this type is consistently inscribed as IMP PROBVS P F AVG, which expands as Imperator Probus Pius Felix Augustus. This epigraphic formula was the quintessential titular assertion of third-century Roman sovereigns, combining the traditional commander's title Imperator with the virtues of piety (Pius) and good fortune (Felix), culminated by the supreme title of Augustus. The reverse presents an epigraphic variant documented within the catalogue entry. The primary legend reads IOVI CONS PROB AVG, expanding to Iovi Conservatori Probi Augusti (To Jupiter the Preserver of Probus Augustus). A recognized variant records the genitive form as IOVI CONS PROBI AVG, using the full spelling of the imperial name. The letterforms are characteristic of the Rome mint during this phase: neat, upright capitals with slight serif flares at the stroke terminals. Officina markings, placed primarily in the exergual space below the ground line, denote the individual workshop responsible for striking the coin.

Typology and Chronological Classification

In the structural arrangement of Probus's coinage developed by Karl Pink and refined in modern studies, the Rome mint struck across several successive emissions between the autumn of AD 276 and the emperor's death in late AD 282. RIC 173 represents an established element of the Jupiter types produced early within this framework, aligning with the consolidation of power at Rome following the death of Florianus. Within Roman Imperial Coinage, RIC 173 is distinguished from closely related Rome mint issues by its specific combination of obverse bust style and reverse iconography. While other catalogue numbers incorporate different bust drapery, left-facing portraits, or extended reverse legends such as IOVI CONSERVAT, RIC 173 is strictly defined by the radiate cuirassed bust right coupled with the abbreviated IOVI CONS PROB AVG or IOVI CONS PROBI AVG reverse formula. The variation in the spelling of the emperor's name represents an engraver's variant rather than a distinct denomination or minting phase.

Circulation and Hoard Evidence

Antoniniani of Probus from the Rome mint circulated widely across the entire Roman world, reflecting the integrated nature of third-century military logistics and regional tax collection. Massive quantities of Probus's radiates have been recovered from major hoards in Britain, France, Germany, and the Danubian provinces, including the monumental Eauze, Normanby, and Gloucester hoards. Because the Rome mint produced coins intended not only for Italy but also to fund frontier operations, specimens of RIC 173 travelled rapidly along established military supply corridors. In circulation, the thin silver-enriched wash quickly wore off high-relief points, leaving the underlying reddish-brown or dark-toned copper-rich core exposed. The high survival rate of billon radiates from the reign of Probus attests to intensive hoarding behavior by citizens anticipating further monetary debasement or political upheaval, preserving these coins in considerable numbers for modern numismatic study.

References

1. Monnaies de l'Empire romain XII.1: D'Aurélien à Florien (270-276 après J.-C.). Introductory chapters on late third-century monetary organization
2. Online Coins of the Roman Empire: RIC V Probus 173. Type record ric.5.pro.173
3. Der Aufbau der römischen Münzprägung in der Kaiserzeit VI/1: Probus. Numismatische Zeitschrift 73, pp. 13-74
4. The Roman Imperial Coinage, Volume V, Part I. p. 317, no. 173