The history of Chester extends back nearly two millennia, covering all periods of British history in between then and the present day. The city of Chester was founded as a fort, known as Deva, by the Romans in AD 79. The city was the scene of battles between warring Welsh and Saxon kingdoms throughout the post-Roman years until the Saxons strengthened the fort against raiding Danes. Following the Norman Conquest in 1066, Chester came under the Earl of Chester. It became a centre of the defense against Welsh raiders and a launch point for raids on Ireland.