For one thing, they are the parts which lie nearest to Gaul and the rest of the Continent from which the invader would be likely to come. And then you will see that the south and east, say as far north as the Humber and as far west as the Severn, are, in spite of certain high ridges of downs and hills, by far the more level, generally, and less broken. They were easier to traverse. We have to imagine all the country far more densely wooded than it is now, and all the river valleys far more marshy. In consequence of the marshy softness of the lower ground, we find that the old tracks generally went along the uplands, wherever that was possible. Colchester, in Essex, was the chief city of Britain when the first serious Roman invasion came, and under Claudius the legions crossed the Thames, took Colchester and mastered all the south-east of Britain. Wherever the Romans came, it was their custom to make military roads if they had any intention of settling in the country. Julius Cæsar's expedition we have to regard as little more than one of discovery--to see what the island was like, and whether its products would pay the Empire for the cost of conquest. His decision must have been that it was worth the cost, because we know that several of the emperors had designs for making the conquest, but, busy as they were elsewhere, nothing was done to achieve it until Claudius came to the throne in Rome. The produce that the Romans found, which induced them to think that the island was worth conquering, was chiefly mineral; tin, lead and iron, with a little gold; and later Britain grew corn for the Empire. The Brythons seem to have been stubborn fighters. They had horses and chariots, with blades, like scythes, sticking out from the sides of the chariots. But it seems that they had little discipline and little idea of forming themselves into any order when they went {6} into battle. They could have had no real chance against the experience and skill, to say nothing of the better arms, of the Roman soldiers.