The fortress was garrisoned by the legion until at least the late 4th century. Although the army had abandoned the fortress by 410 when the Romans retreated from Britannia, the Romano-British civilian settlement continued (probably with some Roman veterans staying behind with their wives and children) and its occupants probably continued to use the fortress and its defences as protection from raiders from the Irish Sea. After the Roman troops withdrew, the Romano-British established a number of petty kingdoms. Chester is thought to have become part of Powys. Deverdoeu was a Welsh name for Chester as late as the 12th century (cf Dyfrdwy, Welsh for the river Dee). Another, attested in the 9th-century History of the Britons traditionally attributed to Nennius, is Cair Legion (“Fort” or “City of the Legion”); this later developed into Caerlleon and then the modern Welsh Caer. (The town’s importance is noted by its taking the simpler form in each case, while Isca Augusta in Monmouthshire, another important legionary base, was known first as Caerleon on the Usk, and now as Caerleon). King Arthur is said to have fought his ninth battle at the “city of the legions” (Caerlleon) and later St Augustine came to the city to try to unite the church, and held his synod with the Welsh Bishops. In 616, Athelfrith of Northumbria defeated a Welsh army at the brutal and decisive Battle of Chester, and probably established the Anglo-Saxon position in the area from then on. The Northumbrian Anglo-Saxons used an Old English equivalent of the British name, Legaca¦stir, which was current until the 11th century, when, in a further parallel with Welsh usage, the first element fell out of use and the simple name Chester emerged. In 689, King Athelred of Mercia founded the Minster Church of West Mercia on what is considered to be an early Christian site: it is known as the Minster of St John the Baptist, Chester (now St John’s Church) which later became the first cathedral. Much later, the body of Athelred’s niece, St Werburgh, was removed from Hanbury in Staffordshire in the 9th century and, to save it from desecration by Danish marauders, was reburied in the Church of SS Peter & Paul - later to become the Abbey Church (the present cathedral). Her name is still remembered in St Werburgh’s Street which passes alongside the cathedral, and near the city walls.