A conflict between Bishop Wilfrid of York and the church and secular establishment led to Wilfrid's expulsion from Northumbria and the division of his vast diocese, and Æthelred sided with Ecgfrith against Wilfrid. After Ecgfrith's death in 685, Archbishop Theodore arranged a reconciliation between Wilfrid and Aldfrith, Ecgfrith's successor, but in 692 Aldfrith and Wilfrid fell out and Wilfrid went into exile in Mercia. Æthelred now supported Wilfrid, making him bishop of the Middle Angles, and defending him at the Council of Austerfield in about 702, when Wilfrid argued his case before an assembly of bishops led by Archbishop Berhtwald of Canterbury. Æthelred's support for Wilfrid embroiled him in dispute with both Canterbury and Northumbria, and it is not clear what his motive was, though it may be relevant that some of Wilfrid's monasteries were in Mercian territory.