Complex sentence: East Anglia briefly strove for independence after 796, the year that Offa was succeeded by his son Ecgfrith, who himself died after a rule of only five months, to be succeeded by a distant kinsman, Coenwulf.
Split into simpler sentences: East Anglia briefly strove for independence after 796, the year that Offa was succeeded by his son Ecgfrith. Ecgfrith died after a rule of only five months and was succeeded by a distant kinsman, Coenwulf.