Caledonian Maeatae Versus Septimius Severus

In 200 AD, the tribes had merged into two main groups.

There are two principal races of the Britons, the Caledonians and the Maeatae, and the names of the others have been merged in these two. The Maeatae live next to the cross-wall which cuts the island in half, and the Caledonians are beyond them. Both tribes inhabit wild and waterless mountains and desolate and swampy plains, and possess neither walls, cities, nor tilled fields, but live on their flocks, wild game, and certain fruits;  for they do not touch the fish which are there found in immense and inexhaustible quantities. They dwell in tents, naked and unshod, possess their women in common, and in common rear all the offspring. Their form of rule is democratic for the most part, and they are very fond of plundering; consequently they choose their boldest men as rulers. They go into battle in chariots, and have small, swift horses; there are also foot-soldiers, very swift in running and very firm in standing their ground. For arms they have a shield and a short spear, with a bronze apple attached to the end of the spear-shaft, so that when it is shaken it may clash and terrify the enemy; and they also have daggers. They can endure hunger and cold and any kind of hardship; for they plunge into the swamps and exist there for many days with only their heads above water, and in the forests they support themselves upon bark and roots, and for all emergencies they prepare a certain kind of food, the eating of a small portion of which, the size of a bean, prevents them from feeling either hunger or thirst.

Such is the general character of the island of Britain; such are the inhabitants of at least the hostile part of it. For it is an island, and the fact, as I have stated, was clearly proved at that time. Its length is 951 miles, its greatest breadth 308, and its least 40. Of all this territory we hold a little less than one half.

Severus, accordingly, desiring to subjugate the whole of it, invaded Caledonia. But as he advanced through the country he experienced countless hardships in cutting down the forests, levelling the heights, filling up the swamps, and bridging the rivers;  but he fought no battle and beheld no enemy in battle array. The enemy purposely put sheep and cattle in front of the soldiers for them to seize, so that they might be lured on still further until they were worn out; for in fact the water caused great suffering to the Romans, and when they became scattered, they would be attacked. Then, unable to walk, they would be slain by their own men, to avoid capture, so that a full fifty thousand died. But Severus did not desist until he approached the extremity of the island. Here he observed most accurately the variation of the sun’s motion and the length of the days and the nights in summer and winter respectively.  Having thus been conveyed through practically the whole of the hostile country (for he actually was conveyed in a covered litter most of the way, on account of his infirmity), he returned to the friendly portion, after he had forced the Britons to come to terms, on the condition that they should abandon a large part of their territory.

Reference

Roman History  LXXVII Cassius Dio