The Romans invaded Britain twice; the first invasion was in 55 B.C. during Julius Caesar's campaign against the Gauls. A century later, in 43 A.D., the Romans invaded again under the emperor Claudius; this time the Romans successfully conquered Britain for several centuries.
The first invasion of Britain was an extension of Caesar's campaign in France, where the Britons had been helping the Gauls repel the Romans. Caesar sent soldiers to retaliate in 55 B.C. and again in 54 B.C., but eventually withdrew from Britain in order to focus on Gaul. In 43 A.D., however, the Roman conquest of Britain started in the southeast and continued over the next century in a series of skirmishes and tribal wars. Although Britain was never fully under Roman control, most of England and Wales and some of Scotland was a Roman territory at the Roman Empire's height.