Caligula Orichalcum Sestertius, RIC I (second edition) Gaius/Caligula 32

Monetary Context and Imperial Donatives

Under the monetary system established by Augustus, the sestertius functioned as the premier large-denomination base-metal coin of the Roman Empire, valued at four asses, two dupondii, or one-quarter of a silver denarius. Cast and struck in orichalcum (a bright golden copper-zinc alloy), sestertii possessed broad flans that offered an expansive canvas for dynastic and political messaging. Upon succeeding Tiberius in March of AD 37, Caligula faced the immediate necessity of legitimizing his rule and fulfilling Tiberius's testamentary bequests to the army and the praetorian guard. Caligula substantially increased these disbursements from his personal inheritance, presenting each praetorian guardsman with a massive donative of one thousand sestertii. Type RIC 32 is intimately connected to this accession transaction, embodying in durable metal the direct financial and political covenant between the new emperor and his military protectors.

Production Standards and Mint Attribution

The entire emission of RIC I (second edition) Gaius/Caligula 32 was struck at the principal imperial mint located in Rome. Caligula re-energized the capital mint after the relatively sparse base-metal output of Tiberius's final decade, ordering massive emissions of heavy aes coinage. The standard sestertius of this period was struck on carefully prepared, heavy orichalcum blanks exhibiting a targeted nominal weight of approximately 27 to 28 grams, with observed specimens across the wider series fluctuating between 24 and 30 grams. Diameters consistently range between 34 and 37 millimeters. Flans were cast in individual molds or open sprues and then hammer-struck between engraved bronze or iron dies. The execution shows remarkable technical sophistication and high relief, characteristic of the finest master engravers operating in Rome during the early Julio-Claudian era.

Obverse Iconography

The obverse presents a realistic, left-facing portrait bust of Caligula, shown bare-necked and wearing a laurel wreath tied with fillets at the nape of the neck. The portraiture is idealized yet distinctive, showing the youthful princeps with cropped locks arranged neatly across the forehead, deep-set eyes, and a sharp profile reflecting typical Julio-Claudian dynastic features. The direction of the portrait facing left is standard for this specific type, contrasting with the right-facing portraits common on ordinary currency of the period. The portrait is framed by a continuous peripheral legend running clockwise from the lower left.

Reverse Iconography and the Absence of S C

The reverse iconography represents the first appearance of the adlocutio scene on Roman imperial coinage. Caligula stands bare-headed and dressed in a civic toga on a low rectangular tribunal on the right, his right arm outstretched in the classical oratorical gesture (adlocutio) toward an assembly of five soldiers standing before him. The soldiers are depicted wearing crested helmets, holding oval shields, and equipped with parazonia at their waists. The two rearmost soldier pairs hold aloft military standards topped with aquilae (eagles). Uniquely among Caligula's sestertii, the reverse completely lacks the standard senatorial authorization formula S C (Senatus Consulto). Numismatists have long recognized that this omission underlines the purely imperial and military character of the issue, which was likely distributed directly from imperial funds rather than regular senatorial treasury channels.

Epigraphic Formulae and Titulature

The obverse legend reads C CAESAR AVG GERMANICVS PON M TR POT, abbreviating 'Gaius Caesar Augustus Germanicus, Pontifex Maximus, Tribunicia Potestate'. Caligula highlights his descent through his celebrated father Germanicus while claiming the supreme titles of Augustus and chief pontiff. Crucially, the absence of an iterating numeral following TR POT indicates that the dies were prepared during his first annual tribunician term. The reverse carries the concise military inscription ADLOCVT COH in the exergue or upper field, abbreviating 'Adlocutio Cohortium' (Address to the Cohorts). This legend explicitly confirms the event depicted as an official address to the praetorian cohorts stationed in Rome.

Typology and Chronological Classification

In the revised classification of Roman Imperial Coinage Volume I, C.H.V. Sutherland classified the adlocutio sestertii under sequential catalogue numbers based on epigraphic changes corresponding to Caligula's successive renewals of tribunician power. RIC I (second edition) Gaius/Caligula 32 represents the initial issue, struck between March AD 37 and March AD 38, identified by the simple unnumbered TR POT legend. Later iterations of the reverse type appear with TR POT II (RIC 33), TR POT III (RIC 40), and TR POT IIII (RIC 48), recording subsequent renewals up to Caligula's assassination in AD 41. RIC 32 is thus securely established as the inaugural edition struck for Caligula's formal accession and subsequent distribution of the praetorian bequest.

Circulation, Survival, and Modern Evidence

Although conceived as a special donative presentation piece, RIC 32 was fully integrated into the fiduciary bronze currency of the empire and circulated extensively. Wear patterns on recovered specimens across Italy, Gaul, and the Rhine frontier demonstrate that these heavy sestertii remained active in daily commerce for decades, frequently circulating alongside later Claudius and Nero brass issues. Following Caligula's assassination and subsequent condemnation of memory by the Senate, many of his portraits and inscriptions suffered selective defacement or countermarking, though surviving RIC 32 coins show that systematic destruction was never entirely completed.

References

1. Coins of the Roman Empire in the British Museum, Volume I: Augustus to Vitellius. pp. 151-152, nos. 33-35
2. Online Coins of the Roman Empire: RIC I (second edition) Gaius/Caligula 32. ric.1(2).gai.32
3. The Roman Imperial Coinage, Volume I: From 31 BC to AD 69 (Revised Edition). p. 110, no. 32