Cwenthryth was an early 9th century Mercian princess, the daughter of Coenwulf of Mercia

Coenwulf of Mercia

Coenwulf was King of Mercia from December 796 to 821. He was a descendant of a brother of King Penda, who had ruled Mercia in the middle of the 7th century. He succeeded Ecgfrith, the son of Offa; Ecgfrith only reigned for five months, with Coenwulf coming to the throne in the same year that Offa...

 and sister of Saint Cenelm. After Coenwulf's death, his son was killed fighting the Welsh, possibly due to Cwenthryth's treachery

Treachery

Treachery is a statutory offence in Australia. There was also an unrelated statutory offence bearing that name in the United Kingdom, but it has been abolished. Both of these offences were derived from or inspired by the related offence of treason. The name treachery was chosen because it is a...

.

She was also the Abbess of Minster-in-Thanet

Minster-in-Thanet

Minster-in-Thanet, also known as Minster, is a village and civil parish in the Thanet District of Kent, England. The village is situated to the west of Ramsgate and to the north east of Canterbury; it lies just south west of Kent International Airport and just north of the River Stour...

 who inherited property and authority from King Coenwulf of Mercia

Coenwulf of Mercia

Coenwulf was King of Mercia from December 796 to 821. He was a descendant of a brother of King Penda, who had ruled Mercia in the middle of the 7th century. He succeeded Ecgfrith, the son of Offa; Ecgfrith only reigned for five months, with Coenwulf coming to the throne in the same year that Offa...

. Wulfred

Wulfred

Wulfred was an Anglo-Saxon Archbishop of Canterbury in medieval England. Nothing is known of his life prior to 803, when he attended a church council, but he was probably a nobleman from Middlesex. He was elected archbishop in 805 and spent his time in office reforming the clergy of his cathedral...

, Archbishop of Canterbury

Archbishop of Canterbury

The Archbishop of Canterbury is the senior bishop and principal leader of the Church of England, the symbolic head of the worldwide Anglican Communion, and the diocesan bishop of the Diocese of Canterbury. In his role as head of the Anglican Communion, the archbishop leads the third largest group...

, challenged her for authority of her abbey estates, and they fought each other for control.