Romans invaded Britain in 55 B.C. but they conquered it only ten year after, under Emperor Claudius. While the North and the West remained under military occupation, the South-East became Romanized.
The practical Roman’s spirit was immediately recognizable. They built towns, road, they brought their culture and language. About the towns, there were three different type of them: the coloniae, peopled by Romans settlers; the municipia, were inhabitants became Roman citizens; and the civitates, where the old Celtic tribes still stayed. Many of these towns were army camps, and the Latin name castra, has remained in many modern town names ending in ‘caster’, ‘chester’ or ‘chester’.
Romans tried to conquer the North, but they didn’t succeeded, so the Emperor Hadrian ordered to build a wall in order to mark out the limits of conquered area.
Roman control was not endless, it finished when Roman soldiers were withdrawn to defend Rome against the Barbarian raiders.
In these circumstances we probably know the legends of King Arthur because a monk wrote about a Romano-British leader, Ambrosious Aurelianus, who bravely fought against the Saxon invaders.