But if inflations played a major role in destroying Roman stability in the third century, there is also the other, more conventional cause to be considered, the part played by the barbarian attacks from without.
The most obvious example of this was the continuing pressure from the Germanic tribes. Inside Germany, the Germanic tribes themselves had undergone major changes, moving away from the comparatively simple tribal organisation of the first century to a more military efficient chieftain organisation, with the emergence of chiefs willing sometimes to act as mercenaries for the Romans and sometimes to act as invaders for themselves
In the middle of the century in particular there was heavy raiding across both Rhine and Danube. In 259, the Alamanni, whose name is preserved in the French name for Germany Allemagne, raided widely: in 267 Goths raided the Balkans and Greece and even Athens was sacked. Most notably of all, in Germany itself, the upper German frontier or Limes was lost. When the Roman frontier was established in Germany along the line of the Rhine and the Danube, a shortcut was taken across southwest Germany and a border line was constructed not unlike Hadrian’s Wall running from the region of Mainz to near Regensburg on the Danube, — some 550 km long in all. However some time in between 250 and 282 this was given up, and the regular German defence took a much longer route down the Rhine to Switzerland and then along the Danube from Switzerland to the Balkans.
Britain however was more prosperous. For one thing in the barrier to the North was settled. Septimius Severus had carried out in major raids into Scotland penetrating as far north as Aberdeen. If the intention was to conquer Scotland; he was certainly not successful, but as a punitive expedition it was very successful, and the Picts and Caledonians in Scotland appear to have been largely cowed by this display of strength.
He also re-established the border to the north. Hadrian had built a wall across northern Britain from Carlisle to Newcastle, but barely 20 years later, his successor Antoninus Pius moved the wall hundred miles to the north and built the Antonine wall from Glasgow to Edinburgh. This too did not last long, and between the 160s and the end of the century there was a sort of limbo when the Antonine Wall was more or less abandoned, and Hadrian’s Wall was to some extent reoccupied. But Severus rebuilt Hadrian’s Wall almost from scratch, so much so that when archaeologists first began to study Hadrian’s Wall, many believed it was the wall is not of Hadrian but of Severus.
But as a result of all this, in the third century peace appears to have been largely won along the wall with little sign of major new activity. Indeed it is even possible that inflation benefited the soldiers along the frontier. In the Roman empire, the money supply came from payments to the troops, and in an inflationary situation, those nearest the money supply benefit most, because they are able to use the new bad money to buy goods at the old (lower) prices: it takes time for the bad money to make its way to the south.
However it has been argued that Britain benefited from the disruption on the Continent which caused an influx of refugees from Germany and Gaul. With the Germans rampaging across much of Gaul in the 270s, suddenly Britain appeared to be a haven of peace and it has been argued that the wealthy villas that appear in the Cotswolds and the West of Britain in the fourth century may have been the result of panic buying by wealthy refugees from Gaul.
But from the Roman point of view, Germany was the lesser threat: the major threat came from the East, from the newly emerging Sassanian empire, in Persia. Here a major new dynasty arose which lasted from 229 to 651. Persia had had its ups and downs ever since the great days when the Persian army almost overwhelmed the Greeks: the Achaemenids were conquered by Alexander the Great, but his successors in their turn were replaced by the Parthians.
However the big change came with the rise of the Sassanians, who under their great ruler Shapur (c.240 – 270) , expanded enormously. Military they were extremely successful and in 260 they even succeeded in conquering and capturing the Roman emperor Valerian, and held him captive for three years until his death, using him, according to a late Christian source, as a footstool for Shapur when mounting his horse.
The Sassanians continued to be a major force in the east until their conquest by the Islamic forces in 651: indeed, it can be argued that much of the Islamic art and culture came from the Sassanians. The original Islamic religion rose in the Arabian desert, where the mobile tribesmen with little time for arts and culture. But when the Moslems conquered the Sassanians, they took over their sophisticated art and culture, and much of what we consider to be Moslem culture, is in fact Sassanian.
But all these military threats on the borders meant that more troops were needed, and more troops meant more money to pay them. And the money paid as bribes to the barbarians drained the Roman empire of its gold. It is said that more Roman gold coins of the third century have been found in Denmark than have been found in Rome itself.
Nevertheless much of the original social structure that had given Rome its strength still remained intact. True, the structure of command in the army had changed. Whereas before, provinces were largely commanded by senators drawn from a largely hereditary senatorial class whose military knowledge tended to be somewhat amateur and who were often stronger at administration than war, in the third century they tended to be replaced by equestrians, that is knights, who tended to be professional soldiers who had risen from the ranks – or whose father had risen from the ranks. This in its turn lead to problems in that they were rather more inclined to rebel when things went wrong and had little of the loyalty of the old senatorial class to the concept of Rome and the Roman emperor.
The position of the soldiers too was changing. Previously being a soldier had been something of a good career move. The auxiliary soldiers served 20 years but at the end of the time you were demobbed with a formal diploma and became a Roman citizen. Thus the ranks of the Roman citizenship were constantly replenished by retired soldiers, often originally recruited as barbarians in other parts of the empire: at the end of the third century, a succession of strong emperors (Aurelian, Diocletian and Constantine) all came from the Balkans, clearly a breeding place for strong and competent men. However in 212, Caracalla had declared that all free men in the Roman Empire were to be Roman citizens (the Constitutio Antoniniana). According to Dio, this was mainly done to increase the tax base, as only full citizens were liable for the whole range of taxes, but inevitably it also meant that service in the Roman army was not as valued as it was before and paradoxically this apparently benign improvement meant that Rome began to lose some of its cohesion. The Roman empire survived, indeed in some respects it was to become even richer in the fourth century. But inflation, and the social changes that were taking place, were beginning to sow the roots of its ultimate decline and fall.
On to Diocletian