Æthelred was King of Mercia from 675 until 704. He was the son of Penda of Mercia and came to the throne in 675, when his brother, Wulfhere of Mercia, died. Within a year of his accession he invaded Kent, where his armies destroyed the city of Rochester. In 679 he defeated his brother-in-law, Ecgfrith of Northumbria, at the Battle of the Trent: the battle was a major setback for the Northumbrians, and effectively ended their military involvement in English affairs south of the Humber. It also permanently returned the kingdom of Lindsey to Mercia's possession. However, Æthelred was unable to re-establish his predecessors' domination of southern Britain. He was known as a pious and religious king, and made many grants of land to the church. It was during his reign that Theodore, the Archbishop of Canterbury, reorganized the church's diocesan structure, creating several new sees in Mercia and Northumbria. Æthelred befriended Bishop Wilfrid of York when Wilfrid was expelled from his see in Northumbria; Æthelred made Wilfrid Bishop of the Middle Angles during his exile, and supported him at the synod of Austerfield in about 702, when Wilfrid argued his case for the return of the ecclesiastical lands he had been deprived of in Northumbria. (Full article...)