Hannibal's attack on Rome is considered to be one of the greatest military feats of all time – even if it did end in defeat for the Carthaginians. Now researchers have solid scientific proof to suggest that the Second Punic War (218-201 BCE) was a turning point in Roman history, transforming what was, at the time, a regional power into one of the world's most notorious empires. And it all comes down to a handful of Roman coins made from Spanish silver.

The Second Punic War kicked off when Hannibal and his army (of men, horses, and elephants) crossed the Pyrenees and Alps to arrive in Northern Italy. After some initial success, the Carthaginian's were defeated and forced to hand over their territory in the Western Mediterranean, as well as some pretty hefty reparations. 

This meant that the Carthaginians, who had once been the leading economic and political power in the region, were left only with their territory in Northern Africa. Meanwhile, the reparations and Iberian silver mines acquired by the Romans during the war paved the way for the Roman Empire.

The role of Spanish silver in the rise of the Roman Empire has long been acknowledged, but research presented at this year's Goldschmidt geochemistry conference (August 13-18 , 2017) was the first to study the silver content in Roman coins.

The researchers, led by Professor Fleur Kemmers and Dr Katrin Westner from the Institute for Archaeological Sciences at Goethe University in Frankfurt, analyzed the isotopic structures of 70 Roman coins using a process called mass spectrometry to determine their country of origin. The coins date from 310-300 BCE to 101 BCE, a period that brackets the Second Punic War. 

They discovered differences in the isotopic signatures of lead between coins before 209 BCE and those after 209 BCE. Those in the later coins correspond to deposits in southeast and southwest Spain, whereas those of earlier coins derive from the same sources of coinage found in Greek cities in Sicily and Italy. This shows just how pervasive Spanish silver was after the Second Punic War and how important it was to the rise of Rome, which was until now just speculation.

"This massive influx of Iberian silver significantly changed Rome's economy, allowing it to become the superpower of its day," explains Westner. "We know this from the histories of Livy and Polybius and others, but our work gives contemporary scientific proof of the rise of Rome."What our work shows is that the defeat of Hannibal and the rise of Rome is written in the coins of the Roman Empire."