Since 2002, I’ve had ample time to reflect on the Roman soldiers who once guarded Hadrian’s Wall. They certainly never struck me as afraid of anything. Then again, they weren’t exactly Roman, either. They came chiefly from foreign lands, principally Belgium and Holland, which were in those days still as uncivilized as the regions north of the wall. Everything they knew of building and writing, they had learned in the service of Rome.

As for the Romans, they preferred to let others fight their battles. They had become the definitive bearers of civilization and as such were the target of a familiar complaint: that they had lost their edge. Comfortable behind their city walls and their foreign guards, they had grown soft. They were politicians and philosophers, bread makers and blacksmiths, anything but fighters.

The Roman poet Ovid knew a thing or two about the soft life, but he also had the unusual experience of learning what life was like for Rome’s frontier troops. The latter misfortune came as a consequence of his having offended the emperor Augustus. The offense was some peccadillo — Ovid never divulges the details — compounded by his having penned a rather scandalous book on the art of seduction. “What is the theme of my song?” he asked puckishly, in verse. “Nothing that’s very far wrong.” Augustus disagreed. Reading Ovid’s little love manual, the moralistic emperor saw plenty of wrong. He probably never even made it to the section where Ovid raved about what a great ruler he was. Augustus banished the poet from Rome, exiling him to Tomis, a doomed city on the coast of the Black Sea, 60-odd miles south of the Danube.

Tomis was a hardscrabble sort of place, a former Greek colony already some 600 years old by the time of Ovid’s exile in the first century AD and no shinier for the wear. Its distinguishing characteristics were exactly two: First, it was about as far from Rome as one could be sent. Second, it lay perilously close to some of Rome’s fiercest enemies, in an area that didn’t yet have a border wall. Like northern Britain, the region of Tomis would one day receive its share of border walls, but in Ovid’s day, the only barriers to invasion were the fortifications around the city itself.

Ovid suffered in his new home. It was one thing to live in a walled city, but quite another to be completely confined within those walls. In his letters to Rome, Ovid complained that the farmers of Tomis couldn’t even venture out onto their fields. On the rare occasion when a peasant dared to visit his plot, he guided the plow with one hand while carrying weapons in another. Even the shepherds wore helmets.

Fear permeated everyday life in Tomis. Even in times of peace, wrote Ovid, the dread of war loomed. The city was, for all intents and purposes, under perpetual siege. Ovid likened the townspeople to a timid stag caught by bears or a lamb surrounded by wolves.

Occasionally, Ovid reminisced on his former life in the capital, where he’d lived free from fear. He wistfully recalled the amenities of Rome — the forums, the temples, and the marble theaters; the porticoes, gardens, pools, and canals; above all, the cornucopia of literature at hand. The contrast with his new circumstances was complete. At Tomis, there was nothing but the clash and clang of weapons. Ovid imagined that he might at least content himself with gardening, if only he weren’t afraid to step outside. The enemy was quite literally at the gates, separated only by the thickness of the city’s wall. Barbarian horsemen circled Tomis. Their deadly arrows, which Ovid unfailingly reminds us had been dipped in snake venom, made pincushions of the roofs in the city.

The birth of walls set human societies on divergent paths, one leading to self-indulgent poetry, the other to taciturn militarism.

There remained a final indignity for Ovid: the feeble, middle-aged author was pressed into service in defense of Tomis. As a youth, Ovid had avoided military service. There was no shame for shirkers back in Rome, a city replete with peaceniks and civilians. Now aging, Ovid had finally been forced to carry a sword, shield, and helmet. When the guard from the lookout signaled a raid, the poet donned his armor with shaking hands. Here was a true Roman, afraid to step out from behind his fortifications and hopelessly overwhelmed by the responsibility of defending them.

From time to time, a Chinese poet would find himself in a situation much like Ovid’s. Stationed at some lonely outpost on the farthest reaches of the empire, the Chinese, too, longed for home while dreading the nearness of the barbarians. “In the frontier towns, you will have sad dreams at night,” wrote one. “Who wants to hear the barbarian pipe played to the moon?” Sometimes they meditated on the story of the Chinese princess who drowned herself in a river rather than cross beyond the wall. Even Chinese generals lamented the frontier life.

Oddly, none of these sentiments appear in the letters written by the Roman soldiers at Vindolanda. Transplanted to a rainy land far from home, they grumbled at times about the beer supply but had nothing to say about shaky hands or sad dreams. It was as if these barbarian-turned-Roman auxiliaries had come from another world, where homesickness and fear had been banished. Perhaps they had.