The Roman departure from Britain was completed by 410. The archaeological records of the final decades of Roman rule show undeniable signs of decay. Urban and villa life had grown less intense by the fourth quarter of the fourth century, pottery shards are not present in levels dating past 400, and coins minted past 402 are rare. So when Constantine III was declared Emperor by his troops in 407, and crossed the channel with the remaining units of the British garrison, effectively Roman Britain ended. The inhabitants were forced to look to their own defences and government -- a fact made clear in a rescript the emperor Flavius Augustus Honorius sent them in 410.

Constantine III, Roman usurper

Roman Britain