A glimpse into the Roman finances of the Second Punic War through silver isotopes

The defeat of Hannibal's armies at the culmination of the Second Punic War (218 BC-201 BC) was a defining moment in Western world history. One of the underappreciated consequences of the conflict was the Roman monetary reform of 211 BC, which ushered in a monetary system that would sustain Roman power for the next many centuries. This system would encapsulate many of the issues plaguing finances of governments until today, such as inflation, debasement, and the size of monetary mass. Here we approach the issue of financial fluxes using a newly developed powerful tracer, that of silver isotopic compositions, in conjunction with Pb isotopes, both of which we measured in Roman coinage minted before and after the 211 BC monetary reform. The results indicate that pre-reform silver was minted from Spanish metal supplied by Carthage as war penalty after the First Punic War, whereas post-reform silver was isotopically distinct and dominated by plunder, most likely from Syracuse and Capua. The 211 BC monetary reform and the end of debasement, therefore, were aimed at accommodating new sources of silver rather than being the response to financial duress. The drastic weight reduction of silver coins implemented by the Roman mint was not motivated by metal shortage but by the need to block inflation after a major surge of war booty.