Ecgfrith of Northumbria in the context of "Æthelred of Mercia"

St Paul's Church, Jarrow, is a Church of England parish church in the Parish of Jarrow and Simonside, on the south bank of the River Tyne in northern England. It was founded in 681 as a part of the Monkwearmouth–Jarrow Abbey. Most of the church is later, but the chancel is the remains of a free-standing chapel of the original monastery. Above the chancel arch is a dedication stone dating to 23 April 685, making this one of, if not the, oldest church dedication stones in England. The Church was dedicated to St Paul by King Ecgfrith and Abbot Ceolfrith. The priest and scholar Bede spent most of his life at the monastery and almost certainly worshipped in the oldest part of the church.

Northumbria, a kingdom of Angles, in what is now northern England and south-east Scotland, was initially divided into two kingdoms: Bernicia and Deira. The two were first united by King Æthelfrith around the year 604, and except for occasional periods of division over the subsequent century, they remained so. The exceptions are during the brief period from 633 to 634, when Northumbria was plunged into chaos by the death of King Edwin in battle and the ruinous invasion of Cadwallon ap Cadfan, king of Gwynedd. The unity of the Northumbrian kingdoms was restored after Cadwallon's death in battle in 634.

Another exception is a period from about the year 644 to 664, when kings ruled individually over Deira. In 651, King Oswiu had Oswine of Deira killed and replaced by Œthelwald, but Œthelwald did not prove to be a loyal sub-king, allying with the Mercian King Penda; according to Bede, Œthelwald acted as Penda's guide during the latter's invasion of Northumbria but withdrew his forces when the Mercians met the Northumbrians at the Battle of Winwaed. After the Mercian defeat at Winwaed, Œthelwald lost power and Oswiu's own son, Alchfrith, became king in his place. In 670, Ælfwine, the brother of the childless king Ecgfrith, was made king of Deira; by this point the title may have been used primarily to designate an heir. Ælfwine was killed in battle against Mercia in 679, and there was not another separate king of Deira until the time of Norse rule.

Wilfrid (c. 633 – 709 or 710) was an English bishop and saint. Born a Northumbrian noble, he entered religious life as a teenager and studied at Lindisfarne, at Canterbury, in Francia, and at Rome; he returned to Northumbria in about 660, and became the abbot of a newly founded monastery at Ripon. In 664 Wilfrid acted as spokesman for the Roman position at the Synod of Whitby, and became famous for his speech advocating that the Roman method for calculating the date of Easter should be adopted. His success prompted the king's son, Alhfrith, to appoint him Bishop of Northumbria. Wilfrid chose to be consecrated in Gaul because of the lack of what he considered to be validly consecrated bishops in England at that time. During Wilfrid's absence Alhfrith seems to have led an unsuccessful revolt against his father, Oswiu, leaving a question mark over Wilfrid's appointment as bishop. Before Wilfrid's return Oswiu had appointed Ceadda in his place, resulting in Wilfrid's retirement to Ripon for a few years following his arrival back in Northumbria.

After becoming Archbishop of Canterbury in 668, Theodore of Tarsus resolved the situation by deposing Ceadda and restoring Wilfrid as the Bishop of Northumbria. For the next nine years Wilfrid discharged his episcopal duties, founded monasteries, built churches, and improved the liturgy. However his diocese was very large, and Theodore wished to reform the English Church, a process which included breaking up some of the larger dioceses into smaller ones. When Wilfrid quarrelled with Ecgfrith, the Northumbrian king, Theodore took the opportunity to implement his reforms despite Wilfrid's objections. After Ecgfrith expelled him from York, Wilfrid travelled to Rome to appeal to the papacy. Pope Agatho ruled in Wilfrid's favour, but Ecgfrith refused to honour the papal decree and instead imprisoned Wilfrid on his return to Northumbria before exiling him.