Septimius Severus, was above all a soldier, who fought his way over three rivals to take control of a troubled empire. His main motto was keep the army happy, which he did by increasing the pay of the soldiers by 50% from 600 denarii a year to 900. This meant providing more money, and he soon found he had to resort to debasement. The main Roman coinage hitherto had been silver: but silver is easy to debase by mixing in copper, for at first the addition of copper is not obvious. Debasement by adding copper had already begun in a small way, but it accelerates under Severus.
It was left to his successor Caracalla (211 to 217) to really set inflation going by introducing a new coin. This is generally known today as the Antoninianus, — the original name is not known — but it had a new portrait of the Emperor with rays of sun surrounding his head and thus today they are generally known as radiates. It would appear that a swindle was intended, and that they were meant to be worth two denarii but in fact they only contained the silver of 1½ denarii. This interpretation is controversial, but if a swindle was intended, it does not seem to have worked very effectively, as scales were freely available in the Roman world. Nevertheless the new coin was very successful and the radiates became the typical coin of the third century.
However, inflation was slow to take off. When you have had a steady coinage for two centuries — and although there was a gentle inflation it amounted to less than 1% a year for two centuries, — there is an inbred belief that the coinage is stable and it took some time for the penny to drop and for people to realise that there was so much money in circulation, that the soldiers were being paid so much, that prices needed to rise if there were to be enough goods to go round.
The crucial change seems to have come about in the year 238. This is the year of six emperors who followed each other in swift succession. The winner, if that is the right word, being Gordian III, who was 12 years old at the time and under the control of his mother and a group of senators. Nevertheless someone was in control at the Treasury, and it appears that the denarius, which had been the standard coin since the days of Hannibal, was finally dropped and the radiate became the main coin of exchange.
There was also a crisis in the gold coinage. Augustus had introduced a bimetallic system, whereby the gold aureus was worth 25 silver denarii, and this proportion had more or less remained stable. However in the third century, supplies of gold dry up; or at least gold coins disappear from the hordes that are left behind for archaeologists to study. The reason usually given is that gold flowed abroad. In the east of the Persian empire of the Sassanids was beginning its remarkable rise, and they captured large or demanded large sums of gold coins which inevitably drained gold from the Roman system. Equally Roman gold coins appear in considerable quantities in Germany, outside the Roman empire, and it would appear that huge sums were being paid to German chieftains is to keep them quiet. But whatever the reason, gold, which is normally a reliable source of monetary value, becomes very scarce, and it is the debased Roman silver coinage that becomes the standard.
From 238 for the next 30 years saw the major decline in the Roman Empire as inflation took a grip and Roman emperors followed one another in unmemorable succession. Inflation really went out of control, and between 238 and 265 the silver content of the coinage fell from around 40% to a mere 5% or less – often little more than a silver wash over a copper coin. The years from 260 to 274 mark the lowest ebb of the third century experiences. The northern provinces of the empire, Gaul, Spain and Britain broke away from the Roman empire, and under the usurper Postumus formed their own version of the Roman empire, based on Cologne and the coins of this period are extremely abundant.
The study of the coinage of Roman Britain was put on a new footing by Richard Reece, who divided it up into 27 different ‘coin issue’ periods and provided graphs to show the frequency of coins in each period so that an excavator could compare the coins he had found on his site with those from the province of as a whole and decide whether or not the site is excavating was abnormal. There are three particular spikes when there was excessive coin loss, and the first of these is his period 18 which covers the Gallic empire from 262 to 273.
The usual interpretation of this spike is that it marks a period of extreme inflation, but Richard Reece has also pointed out that this was the period when coin use penetrated down to the lower reaches of Romano British society. Even those in rural sites which have not used coins before now begin to show a steady coin loss, suggesting that this was the time when the whole of Roman Britain became a money economy; there may have been inflation, yes, but it also marks the entry of the agricultural backwaters into the money economy.
Then in 274 on the first of the three great emperors who reorganise the Roman empire came to power. This was Aurelian who having fought his bloody way to power, found himself with a diminished empire. In the north there was the Gallic empire which he eventually succeeded in bringing back into the fold, while in the east, the charismatic Zenobia, queen of Palmyra had established an empire that covered not only the eastern seaboard of the Mediterranean, but also Egypt, and she too had to be fought and eventually defeated.
But the task for which he is best known was to build a new wall round the city of Rome. Rome had last been fortified in the fourth century BC, but this wall had long been obsolete, for in the intervening period, Rome did not need any walls. But now the external threats to such an extent that it became prudent to defend the city with new walls, and the walls that he built are still one of the most impressive monuments of ancient Rome. And then there was the problem of inflation. Aurelian was never one to shrink a challenge, so he rushed in with reforms that proved to be all wrong.
He had an early run-in with the moneyers at the mint who rioted when he tried to reform them: it was suspected they were creaming off some of the silver for themselves. But his major answer was to introduce new gold and silver coins. The silver coins were actually stamped XX I which apparently means that they were in the proportion of 20 parts of copper to one of silver — a substantial improvement on the previous coins. The coins themselves were improved being well struck from carefully prepared dies, and he established 10 official mints round the empire producing the official coins: hitherto many towns,. Especially in the east, had continued to produce their own coinage. However the new coins were not universally used — some provinces did, others continued to use the old coins. Everything was spruced up – bur inflation continued to soar. Did he perhaps introduce the new coinage at the wrong tariff? This was the first attempt in the world’s history to try to break ever accelerating inflation, and it failed dismally. Aurelian, vigorous as he was, only lasted four years before he was assassinated, and his successors proved unable to solve any of the problems facing the empire, and followed one another in rapid succession. Then in 284 one of the greatest Roman emperors fought his way to power: Diocletian. .