The Roman Army had many assets as it marched to battle. So many in fact, that later writers have had a hard time trying to pin down the abilities and assets that lead to victory. Yet no army in history has ever been as successful as the Roman. For 600 years the empire smashed one threat after another. But how? That is the real question and one not easily answered. In this article I will numerate three of those vital assets. These three I feel are the more important factors during that long stretch of Pax Romana. They are not in order of priority or value, but simply a list:
1) Power vacuum: It’s easy to keep the peace if no one arises to challenge your military dominance with a realistic chance of strategic victory over you. During a 600 year span of time no civilization arose that was in anyway able to dictate terms to the Roman’s. Parthia is a frequent offering as a ‘real’ enemy to Rome. This is based on Carrhae, and the smashing nature of that defeat. Yet, Parthia never threatened Rome, in fact their infrequent invasions of Roman provinces always ended in the Parthian’s retreating back to the interior of their empire. Rome burnt Ctesiphon three and possibly five times, no similar event was ever caused by the Parthian’s to Rome. Roman expansion into Parthia was prevented by there being nothing worth conquering. The German barbarians also inflicted a devastating defeat on Varus in the Teutoburg Wald, bad enough that the Roman’s never tried to conquer the Germanic tribes again. But Teutoburg was a battle in line with the Little Big Horn, in that the victor was looking to remove a threat from their territory not to conquer the enemy’s territory. It’s doubtful even with Arminius leading them, the tribes could have retained their solidarity long enough to enter and conquer imperial holdings. As for all other enemy’s: ‘revolt’ against Roman rules was the order of the day.
2) Adaptation: The Roman army was never proud, or at least never too proud to adopt a good idea. The Romans used the best of everything they could find. From Balearic slingers to the finest siege machines from Greece and Persia, the Imperial Army took whatever worked. The Roman’s never believed in ‘silver bullets’ preferring to take a holistic approach to warfare. Rome may have been the first military in the world to study and adopt foreign ideas in such a systematized way, it could be argued that the Romans were the first professionals to take a scientific approach to warfare.
3) Discipline: Few militaries have ever maintained such a high level of discipline and training as the Roman army. This does not mean the Legions were at the peak of readiness at all times. The Legions often took a drubbing before they toughened up and starting winning. But the average Legion needed far less time toughening up to be battle ready.
So if the army was all conquering and able to maintain it’s dominance for 600 years, what on earth beat the Romans? After all the empire did ‘fall’. In the end what ended the dominance of Roman armies was the only enemy capable of consistently defeating a Roman army: The Romans themselves. For two centuries the Roman army fought it’s self as one Roman General after another aimed at the purple. Enough generals were successful that the attempt was worth the blood and treasure spent trying. In the second century civil war became a way of life within the Empire. Emperor after emperor tried to put a system together that kept them on top and the army too busy elsewhere to engage in civil war. It never worked, and in the end the Empire tore itself apart.