Caligula Sestertius, RIC I (second edition) Gaius/Caligula 40

Monetary Context and Denominational System

The sestertius was the premier large base-metal denomination of the early Roman Empire, established as the cornerstone of the daily fiduciary currency by Augustus in his monetary reforms around 23 BC. Valued at four asses or one quarter of a silver denarius, the sestertius was manufactured from orichalcum, a golden-toned copper-zinc alloy known in antiquity for its brilliant appearance and durability. Under Gaius, widely known as Caligula, the production of large aes denominations at Rome was marked by bold, expansive pictorial compositions that utilized the broad diameter of the flan to convey political, dynastic, and military messaging. While regular imperial base-metal issues almost universally carried the senatorial mark S C (Senatus Consulto) to signify senatorial decree in the coining of bronze and brass, RIC 40 famously lacks this formula entirely. Its absence signifies that the type operated under special imperial authority, likely linked directly to imperial donatives, military pay, or the emperor's sovereign prerogative over the praetorian cohorts.

Production, Minting, and Metrology

The issue RIC I (second edition) Gaius/Caligula 40 was produced exclusively at the primary imperial mint in Rome. Struck on substantial orichalcum blanks, specimens of this sestertius family typically reflect the heavy Augustan weight standard, averaging roughly 27 to 29 grams with diameters typically ranging between 34 and 37 millimeters, though individual specimens exhibit natural variations stemming from hand-hammered flan preparation. Dies were cut by senior celators of the urban mint, displaying the crisp, refined portraiture and multi-figure compositional mastery characteristic of Julio-Claudian die-engraving workshops. The metallic composition, rich in zinc, gave newly minted coins a radiant brass finish that distinguished them visibly from pure copper denominations such as the as and quadrans.

Obverse Iconography

The obverse features the left-facing, laureate head of Gaius. The portrait presents classicizing Julio-Claudian traits, with neatly ordered hair brushed forward, a straight profile, and an expressive, slender neck encircled by the laurel wreath of victory and sovereign authority. Unlike many earlier Julio-Claudian base-metal coins that favored right-facing portraits, Caligula's official sestertii predominantly positioned the emperor facing left, creating a distinctive visual identity for his reign. The surrounding inscription runs clockwise along the flan border, framed neatly within an outer linear or beaded circle.

Reverse Iconography and Allocution Scene

The reverse presents a dynamic multi-figure scene depicting an adlocutio, or formal imperial address. The emperor stands bare-headed and dressed in the civil toga on a low platform or suggestum at the right of the field, extending his right arm forward in a gesture of speech and command. Before him stand five soldiers facing right toward the platform, outfitted with military helmets, parazonia (short ceremonial sidearms), and large oval shields. The rearmost pairs of soldiers hold military standards surmounted by eagles (aquilae), denoting the elite status of the cohorts. The legend ADLOCVT COH is positioned horizontally in the upper field or divided across the composition. Strikingly, the letters S C are omitted, making this design one of the few completely non-senatorial base-metal types of the early principate.

Epigraphy and Legend Readings

The obverse legend reads C CAESAR DIVI AVG PRON AVG P M TR P III P P, expanding to Caius Caesar Divi Augusti Pronepos Augustus, Pontifex Maximus, Tribunicia Potestate Tertia, Pater Patriae. This epigraphic formula articulates the complete institutional and dynastic legitimacy of the emperor: great-grandson of the deified Augustus, revered princeps, supreme pontiff, holder of the tribunician power for the third time, and father of the country. The reverse legend ADLOCVT COH is an abbreviation of Adlocutio Cohortium, explicitly identifying the scene as the formal address to the cohorts, widely interpreted by historians as the Praetorian Guard stationed at Rome.

Typology, Dating, and Chronological Evolution

The chronology of RIC 40 is securely established by the tribunician counter in the obverse legend. Gaius assumed his third tribunician power (TR P III) on March 18, AD 39, and held it until March 17, AD 40, fixing the striking of this specific type within that one-year window. This issue forms part of a continuous sequence of adlocutio sestertii initiated earlier in his reign: RIC 32 was struck in AD 37-38 without the Pater Patriae title, followed by RIC 33 in AD 37-38 with P P, and later by RIC 48 in AD 40-41 bearing TR P IIII. RIC 40 thus marks the mid-reign iteration of the adlocutio series, documenting the ongoing reiteration of military allegiance during the complex political developments of AD 39 and 40.

Circulation, Hoard Context, and Afterlife

Although minted at Rome, sestertii of Caligula circulated widely throughout the western provinces of the Roman Empire, including Italy, Gaul, the Rhine frontier, and Hispania. As high-value everyday spending money, they filled an essential economic role in market transactions and administrative disbursements. Following Caligula's assassination in January AD 41, many of his bronze coins suffered deliberate defacement, countermarking, or removal from circulation under Claudius, who allowed the Senate to strike his memory from formal honors. Consequently, specimens of RIC 40 that survived in hoards and river deposits often display intentional gouging across the portrait, countermarks of subsequent regimes, or significant circulation wear from extended secondary usage.

References

1. Coins of the Roman Empire in the British Museum, Volume I: Augustus to Vitellius. pp. 156-157, nos. 67-68
2. Online Coins of the Roman Empire: RIC I (second edition) Gaius/Caligula 40. ric.1(2).gai.40
3. The Roman Imperial Coinage, Volume I: From 31 BC to AD 69 (Revised Edition). pp. 111-112, no. 40
4. Numismatische Untersuchungen zur Funktion der spaetrepublikanischen und fruehkaiserzeitlichen Buntmetallmuenzung. pp. 120-125