For most of the first 250 years of the Roman Empire, its gold aureus was relatively consistent in weight and purity. It was affected only by adjustments in weight – usually downward, but occasionally upward. The first major decline in later history occurred under Caracalla, and subsequently under Severus Alexander. Beginning with the reign of Trebonianus Gallus, however, gold coinage became increasingly variable in weight and denomination, and medallions intended as bonuses or bribes also came to be struck with regularity. Something that certainly can be attributed to Gallus is the mainstream introduction of the ‘binio’, a gold homologue to the silver double-denarius. In some if not all cases, the binio was struck with double-denarius dies, at a heavier weight than the aureus. With the typical aureus of Gallus weighing about 3.60 grams, his average ‘binio’ weighed about 5.75 grams. The binio weighed roughly 1° times as much as the aureus, and if we examine the weight relationship between Caracalla’s silver double-denarius and denarius, we find an identical weight ratio. Furthermore, they are identically different in terms of iconography, thus giving us a perfect parallel. Indeed, had the denarius not been scrapped as a mainstream issue under Gordian III, the same comparison would probably be possible with Gallus’ denarii and double-denarii. Predecessors to the binios of this era were struck by Caracalla. However, only a handful of these have survived, and Caracalla’s truly are double-aurei medallions because their weight is double that of his contemporary aurei.

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Trebonianus Gallus, who was likely born in Perusia in 206, was one of the few barracks emperors with a traditional senatorial background. Having been suffect consul in the 240s, Gallus served as Decius’ legatus pro praetore provinciae Moesiae Superioris in 250/1 while the emperor was campaigning against the Goths in the area. This crucial position of power on the most perilous Roman border and his geographical proximity allowed Gallus to swiftly claim the purple after Decius died in the disastrous Battle of Abritus in mid 251. In defiance of rumors that he had conspired with the victorious Goths, Gallus gained the support of the disorganized remnants of the Roman army and negotiated peace with the invaders before hasting to Rome, where he adopted Hostilian, Decius’ youngest son, to avoid civil war. The prince conveniently died shortly thereafter, allegedly of a plague, whereupon Gallus’ own son Volusian was raised to the rank of Augustus. As it was becoming alarmingly normal, Gallus’ reign, too, was troubled by foreign invasions, both by Gothic tribes as well as by the Sasanid King Shahpur I. The continuous turmoil on the Roman borders eventually led to the emperor’s downfall in 253, when he was killed by his own troops following the revolt of Aemilian. As it would turn out, Gallus’ main legacy was the rise to power of his general Valerian, who would overcome Aemilian and whose dynasty would dominate the empire for the next fifteen years. Numismatically, Gallus is best known for the introduction of the so-called binio, a double-aureus struck from antoninianus dies weighing roughly 1.5 times that of a regular aureus, much like the first Roman antoniniani had weighed 1.5 times that of a denarius at the time of their introduction under Caracalla. Perhaps not surprisingly, this ratio was soon to fall and the few biniones struck in the decades after Gallus varied widely in weight, as did the regular aurei, showing that the Roman gold coinage now predominantly ceased to be struck to a consistent weight standard. When the present, wonderful piece first appeared in the famous Biaggi Collection, biniones of Gallus were virtually unheard of (which resulted in a remarkable hammer price of 58,000 CHF in the Leu 22 sale in 1979), and although a few more have showed up since, this coin is still undoubtedly among the finest known examples, and, perhaps, the most prestigious of them all.

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