Gallienus, 253-268. 'Denarius' (Silver, 20 mm, 2.30 g, 6 h), an 'offstrike' from aureus dies. Rome (?), circa 266-267. GALLIENVS P F AVG Cuirassed bust of Gallienus to left, wearing crested pseudo-Corinthian helmet and balteus, holding spear in his right hand and shield on his left shoulder, cuirass and shield decorated with a gorgoneion. Rev. P M TR P XX (sic!) C VII P P Mars, holding spear in his right hand and round shield in his left, descending right through the air to sleeping Rhea Silvia, reclining left on the ground, naked to waist and with her hands behind her head. Cohen -. Roma XIV (2017), 796 (same obverse die). MIR -. RIC -. Triton XXI (2018), 832 (same dies). Extremely rare, apparently the fourth known specimen, and the second struck from this erroneous reverse die. A fascinating coin that offers significant new insight into the series. Somewhat porous and with a flan crack, otherwise, good very fine.


Gallienus’ extremely rare Rhea Silvia issues are remarkable in many respects. They revive a motif first seen on an as of Antoninus Pius, showing the Vestal Virgin Rhea Silvia approached by Mars, whose union produced Romulus and Remus and thus provided Rome with divine descent from the god of war.

Although the precise reason for this revival remains uncertain, the refined die work and unusually high silver content strongly suggest that these coins were not intended for ordinary circulation. The type was struck first in gold at Mediolanum in 260 and later as silver denarii in 264-265 and again in 266-267 (but see below). They may well have commemorated victories, linking Gallienus with Mars and Rome’s mythical origins - a potent message during the crises that followed Valerian’s capture, the wave of usurpations, and the secession of the Gallic Empire.

What has so far escaped notice, however, is the impossible reference to a twentieth tribunician power. CNG, in their die-matched Triton example, correctly recorded the numeral XX but did not recognize the problem, and even associated it with an eighth consulship - a claim based solely on a misreading by the cataloguer, since the coin clearly shows VII, not VIII. At the time of his assassination in September 268, Gallienus had attained seven consulships but was only in his seventeenth tribunician year; a twentieth, as these denarii record, he never reached.

Until recently, denarii were thought to exist for tribunician years XIII = 264/5 and XV = 266/7. Closer inspection, however, shows that the pieces attributed to the fifteenth year (Roma 14 (2017), 796 and Leu 10 (2021), 2351) were almost certainly misread due to heavy die wear. They too bear XX - an impossible twentieth year. We are therefore not dealing with denarii of TR P XIII and XV, as previously believed, but rather with pieces of the thirteenth year and others carrying the erroneous designation XX = 20.

This raises the inevitable question of why a number appears that Gallienus could never have attained in his lifetime. Unless one accepts the highly unusual hypothesis of an anticipatory issue - comparable to the forward-looking vota coinage of the later Empire - the likeliest explanation is a mint error. As the mistake is found on at least two dies, it was probably already introduced at the stage of the prototype from which the dies were engraved. The most convincing scenario is a confusion between X and V, with XV = 266/7 actually intended, which also accords with the seventh consulship. Whether the prototype itself contained a scribal slip, or whether the V was written so indistinctly as to be mistaken for an X, can no longer be determined. What is certain, however, is that this blunder is a fascinating one, providing valuable insight into the working practices of the Roman mint.