The Roman presence in Britain began with Julius Caesar's expeditions in 55 and 54 BC, which led to little lasting impact. Almost a century later, in 43 AD, Emperor Claudius initiated a full-scale invasion that resulted in the Roman conquest of much of Britain. The Romans ruled Britain for almost 400 years, during which time they built towns, roads, and villas and introduced new systems of government, law, and taxation. The Roman period came to an end in the early 5th century AD as the Roman Empire declined and was forced to withdraw its legions from Britain. The departure of the Romans led to a period of instability and upheaval in Britain, as various groups, including the Britons, Saxons, and Picts, vied for control.