Offa of Mercia

Offa seized Mercia's throne in 757 after civil war and the assassination of his predecessor, defeating the claimant Beornred. Through the 760s and 770s he pressed outward, taking Sussex by 771 and exploiting Kent's weakness to claim overlordship, though his grip on both remained contested. By the 780s he controlled most of southern England: he married his daughter Eadburh to the king of Wessex, became overlord of East Anglia, and in 794 had its king Æthelberht II beheaded, likely for rebellion. He fought the Archbishop of Canterbury and convinced Pope Adrian I to split the archdiocese, creatin…