Wessex expands - Ceawlin

If King Arthur existed, he probably won at Mons Badonicus around 500 AD, and his Kingdom probably lasted 50 years or more.

Cerdic's Grandson Cynric and Great Grandson Ceawlin failed to make any headway for 40 years. But then Cynric captured two British strongpoints - Old Sarum and Barbury Castle.

Then Ceawlin in 577 won a great victory at Hinton Hill near Dyrham, in South Gloucestershire, defeating 3 British Kings - and the dam had burst. Ceawlin was described as a Bretwalda - overlord of all the English. But his reign ended in his personal chaos and despair.

http://historyofengland.typepad.com/blog/2011/01/2-the-west-saxon-bretwalda.html