Complex sentence: In 686 the South Saxons attacked Hlothhere, king of Kent, in support of his nephew Eadric, who afterwards became king of Kent until Kent was invaded by Cædwalla who had managed to establish himself as ruler of Wessex.
Split into simpler sentences: In 686 the South Saxons attacked Hlothhere, king of Kent, in support of his nephew Eadric, who afterwards became king of Kent. Eadric's rule in Kent lasted until Kent was invaded by Cædwalla who had managed to establish himself as ruler of Wessex.