Here at the world's end, on its last inch of liberty, we have lived unmolested to this day defended by our remoteness and obscurity. But there are no other tribes to come, nothing but sea and cliffs. And these more deadly Romans whose arrogance you cannot escape by obedience and self-restraint, to plunder, butcher, steal. These things they misname empire, they make a desolation and they call it peace. Of course, Calgacus never said any such thing. This was a speech written long after the event by Tacitus and it's entirely Roman, not Scottish. Yet this burning sentiment would echo down the generations. Like Britannia itself, the idea of free Caledonia was from the first, a Roman invention. There was one emperor, Spanish by birth, who understood that even the world's biggest empire needed to know its limits. And he of course was destined, in Britain at any rate, to be remembered by a wall.