Chesters Roman Fort,
Roman Britain, known as Britannia was part of the Roman Empire between 43rd and 410th centuries.
Julius Caesar had designs on the British Isles and invaded in the years 55 and 54Bc but was unable to gain a foot hold. It wasn't till 43AD that Claudius gained ground in an invasion that would change the fate of the British Isles. He established a provincial government and pushed north but was stopped in Caledonia. A Romano-British culture developed cementing Roman power in southern Britain.
Hadrian built a wall to form the northern boundary, completed in the 128th century, to maintain an effective boarder. The Romans always pushed forward to gain more land, in the 142nd century the boundary was pushed further north and they built the Antonine wall at the Forth-clyde line but this did not last long. They retreated back to Hadrian's wall in the 160's.
Around 197, Britannia was divided into two provinces, Britannia Superior and Britannia Inferior. Again it was dived further in 293, and made into an imperial diocese. For much of the later period, Britannia was subject to barbarian invasion and often came under the control of imperial usurpers and pretenders. The Romans largely departed from Britain around 410, leading to what is known as the sub-Roman period, but the legacy of the empire was felt for hundreds of years.