IRON Age Cultures north and south of Hadrian’s Wall were already constructing hundreds of mountaintop towns centuries before the Roman Empire was founded.

When militant Roman troops marched into Scottish territory for the first time they knew to expect massive engineering works, trading infrastructure, well-populated settlements, thousands of stone constructions, and a resource-rich province filled with meaningful assets and powerful people. The earliest surveyors of Scotland didn’t find cave people and perpetual conflict. They found civilisation.

Iron Age Scotland wasn’t a Columbus-style discovery for Rome. The first century Roman writer Tacitus might be the earliest to describe “the red hair and large limbs of the inhabitants of Caledonia” and the “boldness in challenging danger” of the Britons, but he also reminds us that the inhabitants had already “been described by many writers” by 98AD.

READ MORE: The mysterious Scots who may have undertaken first European exploration of America

Agricola feared the native’s “superior numbers and their knowledge of the country”, knowing it would give his Roman army a clear disadvantage in virtually every clash. In the Life and Death of Agricola, written just before 100AD, we are told that one Roman encampment was “joyously sharing the same meals” and “dwell[ing] on their own achievements and adventures” somewhere in Scotland when the “tribes inhabiting Caledonia flew to arms, and with great preparations …advanced to attack”.

This understandably “inspired [Agricola] with alarm”. His advisers recommended a total “retreat south”, where the Romans could “retire rather than ... be driven out” of Northern Britain. The commander naively ignored the advice and prepared to defend his encampment.

The approaching attackers may have anticipated this, because “they suddenly changed their plan, and with their whole force attacked by night” instead. The Caledonians “broke into camp” and began slaughtering an entire legion of Romans (who Tacitus identifies as the “nonam legionem” or “Ninth Legion”) after “cutting down the sentries, who were asleep or panic-stricken”.

After each engagement, native forces retained their “arrogant demeanour” and left for their protective woodlands and hill fortifications, where they allegedly began “arming their youth, removing their wives and children to a place of safety, and assembling together to ratify … a confederacy of all their states”.

Roman engagements with Caledonian guerillas would’ve been more successful if, according to Tacitus, “the flying enemy” weren’t perpetually “sheltered by morasses and forests” and their own fortified homes.

“Of all the Britons,” Agricola is alleged to have said, “these are the most confirmed runaways, and this is why they have survived so long.” Agricola and his advisers feared “the enemy’s superiority of force” and were presumably shocked when the “runaways” “poured on us a dense shower of darts”.

Tacitus tells us that “the swords of the Britons are not pointed, and do not allow them to close with the foe, or to fight in the open field”. In an attempt to exploit this perceived deficiency, Agricola tried to meet the guerillas in the open field. The resulting carnage, Tacitus suggests, “had anything but the appearance of a cavalry action, for men and horses were carried along in confusion together, while chariots, destitute of guidance, and terrified horses without drivers, dashed as panic urged them, sideways, or in direct collision” with the rank and file of the Roman war machine.

Tacitus again explains that native fighters in Scotland would repeatedly rally in the woodlands, and “as they knew the ground” were quickly “able to pounce on the foremost and least cautious” invaders.

READ MORE: It's time to end ignorance of Irvine's royal and ancient history

When the bloodshed drew to a close, the Caledonians “fled no longer in masses as before” but expertly dispersed to “the shelter of distant and pathless wilds” – in other words “they went home”.

The so-called conquered states were secured in their own “hill-tops and … without fear for themselves sat idly disdaining the smallness” of the Roman army. The people of Iron Age Scotland were laughing at the vastly outnumbered Romans, who then retreated.

Agricola’s so-called “Battle of Mons Graupius” was immediately hailed as a decisive Roman victory over the tribes of Caledonia, even though it doesn’t fit the description of a battle. Or a victory.