Antoninus Pius Copper As

Monetary Context and Denominational System

During the reign of Antoninus Pius (138 to 161 AD), the Roman monetary system maintained the traditional Augustan denominational hierarchy. Within this bimetallic and base-metal framework, the as served as the benchmark base unit for everyday small-scale retail transactions, wage payments, and fractional market accounting. By imperial tariff, one gold aureus was equivalent to 25 silver denarii, 100 orichalcum sestertii, 200 orichalcum dupondii, 400 copper asses, 800 semisses, and 1600 quadrantes. While the sestertius stood as the standard accounting unit for private estates, public contracts, and imperial largesse, the as was the workhorse of physical daily commerce across the empire. The denomination was distinguished metallurgically from the dupondius: whereas dupondii were struck in yellow orichalcum (a zinc-copper alloy) and depicted the emperor with a radiate crown, asses were manufactured from relatively pure unalloyed copper and normally portrayed the emperor laureate or bare-headed. This metallurgical and iconographic distinction ensured that the public could readily differentiate between the two closely sized denominations despite wear and patina.

Production, Mints, and Metrology

The vast majority of imperial copper asses bearing the name and portrait of Antoninus Pius were manufactured at the central mint in Rome. Operating under the administrative oversight of the imperial equestrian bureaucracy, the mint utilized manual striking techniques with paired bronze dies. Engravers at Rome achieved a high degree of artistic consistency and portrait fidelity across multiple officinae, or operational workshops. Flans were cast in open or two-piece molds before striking, leading to slight irregularities in blank thickness and perimeter shape. In addition to the central mint at Rome, numismatic scholars have noted occasional provincial or secondary mint emissions, particularly in Britannia, where distinctive local style asses depicting Britannia on the reverse were produced, possibly to satisfy acute shortages of fractional small change among stationed legions. In metrological terms, the copper as under Antoninus Pius targeted an average theoretical weight centered roughly between 9.5 and 11.5 grams, with a module typically spanning 25 to 28 millimeters in diameter. Actual specimen weights vary considerably due to the mint's practice of striking base-metal coinages al marco (a fixed number of pieces per Roman pound of copper) rather than al pezzo (weighing each flan individually), combined with inevitable metal loss from prolonged market circulation.

Obverse Iconography and Imperial Image

The obverse of the copper as presents a dignified, classicizing portrait of Antoninus Pius, embodying the Antonine ideal of the philosophical and benign ruler. The emperor is almost universally depicted in mature middle age, with a full, neatly trimmed beard, undulating locks of hair, and an expression of serene gravity. The portrait bust appears in several distinct typological treatments: laureate head right (the most common across all issue phases), laureate head left, bare head right, and occasionally bare head left. Less frequently, the bust includes drapery on the left shoulder, full paludamentum, or a cuirass. Unlike the dupondius, which served as a double-as and almost always exhibited the radiate solar crown, the as maintained the laureate wreath or bare head as an essential visual identifier of its denomination. Over his twenty-three years of rule, the portraiture transitioned subtly from the firmer, idealized likeness established during his initial adoption by Hadrian to a more aged, heavily contoured representation during the mid-150s and early 160s AD, while preserving continuous stylistic harmony.

Reverse Iconography and Programmatic Themes

The reverse types of the asses of Antoninus Pius reflect an ideological program focused on domestic harmony, agricultural abundance, piety toward traditional Roman deities, and civic celebrations. Personifications predominate throughout the series. Annona appears repeatedly with grain ears, a cornucopia, and a modius or the prow of a ship, emphasizing the emperor's duty to guarantee the grain supply of Rome. Pax is shown holding an olive branch and cornucopia or setting fire to collected arms. Felicitas, Aequitas, Salus feeding a serpent, and Moneta holding a balance reinforce themes of internal stability, public health, and financial integrity. Deeply anchored in traditional religion, numerous types celebrate Pietas at an altar or portray major Roman temples, such as the Temple of Divus Augustus or the Octastyle Temple of Rome and Venus. A renowned thematic group struck around 140 to 148 AD commemorated the 900th anniversary of the founding of Rome (the ninth centenary celebrated in 148 AD), utilizing antiquarian and mythological motifs such as Romulus and Remus suckled by the she-wolf, Aeneas carrying Anchises, and Mars descending to Rhea Silvia. Military types appear far less frequently than on the coins of Trajan or Septimius Severus, though significant campaigns in Britain are commemorated by notable types showing Britannia seated on rocks with a shield and military standard.

Inscriptions and Epigraphy

Epigraphy on the copper as followed strict conventions of Roman imperial titulature. The obverse legends systematically record the accumulation of constitutional offices and honors. Upon his accession in 138 AD, early legends read IMP T AEL CAES HADR ANTONINVS, soon augmented by the Senate with the cognomen PIVS. By 139 AD, the standard formulation stabilized around ANTONINVS AVG PIVS P P (Antoninus Augustus Pius, Pater Patriae), frequently expanded with TR P (Tribunicia Potestate) and a consular iteration such as COS II, COS III, or COS IIII. In the later decades of the reign, the legend ANTONINVS AVG PIVS P P TR P followed by regnal numbers from XI through XXIIII became the standard convention. Reverse legends complemented these administrative formulae, either continuing the consular dating (for example, COS IIII or TR POT XX COS IIII) or providing explanatory legends for the depicted motifs, such as ANNONA AVG, PAX AVG, FELICITAS AVG, BRITANNIA, or TRIB POT COS III DESIG IIII. Nearly all imperial asses feature the prominent letters S C (Senatus Consulto) across the reverse field or in the exergue, signifying that the base-metal issue was struck by formal senatorial decree under the emperor's authority.

Typology and Chronological Evolution

The chronological sequence of Antonine asses is established primarily through the regular annual renewal of his tribunician power (TR P), which occurred on December 10 of each year starting in 147 AD (after an initial irregular tenure beginning in 138 AD). Numismatists divide the coinage into four main chronological phases. The first phase spans the accession and early consulships from 138 to 139 AD (COS to COS II), characterized by transitional titles and the formal assumption of the title Pater Patriae. The second phase, from 140 to 144 AD (COS III), witnessed a major expansion of civic personifications and monumental architecture. The third phase covers the emperor's fourth consulship, assumed in 145 AD (COS IIII), extending through the centennial celebrations of 148 AD and into the early 150s AD. This period produced the greatest variety of reverse dies, including the famous mythological and foundation series. The fourth and final phase spans from approximately 153 to 161 AD, during which the annual TR P numbers were regularly engraved on the reverse or obverse (TR P XVI through TR P XXIIII). Alongside the substantive lifetime issues, a posthumous series of consecratio asses was struck under Marcus Aurelius and Lucius Verus following Antoninus Pius's death in March 161 AD, bearing the obverse legend DIVVS ANTONINVS and reverse motifs such as a funeral pyre or an eagle.

Circulation, Hoarding, and Archaeological Context

Copper asses of Antoninus Pius enjoyed extensive and durable circulation throughout the Roman world, particularly in the western and northern provinces such as Gaul, Britannia, Germany, and along the Danubian limes. In these areas, the Roman military and provincial urban economies relied heavily on copper and orichalcum coinages to conduct daily commerce, procure local supplies, and provide small change for legionary stipends. Archaeological site finds from military forts on Hadrian's Wall and the Antonine Wall demonstrate that asses of this reign arrived in significant volume and circulated for decades alongside earlier Flavian, Trajanic, and Hadrianic bronzes. Because copper asses were low in intrinsic value relative to their bulk, they are infrequently found in major savings hoards, which typically favored gold aurei or silver denarii; instead, they dominate excavation contexts, urban drains, temple votive deposits, and civilian settlement lost-coin assemblages. Widespread wear observed on surviving archaeological specimens indicates that these coins remained active in currency well into the third century AD, before the hyperinflation of the crisis period led to the complete abandonment of the traditional fractional denomination.

References

1. Coins of the Roman Empire in the British Museum, Vol. IV: Antoninus Pius to Commodus. pp. 170-360
2. Money and Government in the Roman Empire. Cambridge University Press, 1994
3. The Roman Imperial Coinage, Vol. III: Antoninus Pius to Commodus. pp. 26-174
4. Untersuchungen zur romischen Reichspragung des zweiten Jahrhunderts, Teil III: Die Reichspragung zur Zeit des Antoninus Pius. Stuttgart: Kohlhammer, 1937