How the third century crisis was different than the first and second centuries a period of peace ?
(i) If the first and second centuries were by and large, a period of peace, prosperity and economic expansion, the third century brought the first major signs of internal strain. From the 230s, the empire found itself fighting on several fronts simultaneously.
(ii) In Iran a new and more aggressive dynasty emerged in 225 (they called themselves the ‘Sasanians’) and within just 15 years were expanding rapidly in the direction of the Euphrates. In a famous rock inscription cut in three languages, Shapur I, the Iranian ruler, claimed he had annihilated a Roman army of 60,000 and even captured the eastern capital of Antioch.
(iii) Meanwhile, a whole series of Germanic tribes or rather tribal confederacies (most notably, the Alamanni, the Franks and the Goths) began to move against the Rhine and Danube frontiers, and the whole period from 233 to 280 saw repeated invasions of a whole line of provinces that stretched from the Black Sea to the Alps and southern Germany.
(iv) The Romans were forced to abandon much of the territory beyond the Danube, while the emperors of this period were constantly in the field against what the Romans called ‘barbarians’. The rapid succession of emperors in the third century (25 emperors in 47 years!) Is an obvious symptom of the strains faced by the empire in this period.