Ecgfrith of Northumbria Ecgfrith ( ; c . 645 – 20 May 685 ) was the King of Deira from 664 until 670 , and then King of Northumbria from 670 until his death , succeeding his father Oswiu . He ruled over Northumbria when it was at the height of its power , but his reign ended with a disastrous defeat at the Battle of Nechtansmere in which he lost his life . Early life and kingship of Deira . According to Bede in the " Historia ecclesiastica gentis Anglorum " , Ecgfrith was held as a hostage " at the court of Queen Cynwise in the province of the Mercians " when Penda of Mercia invaded Northumbria in 654 or 655 . Penda was eventually defeated and killed in the Battle of the Winwaed by the Northumbrians under Oswiu , a victory which greatly enhanced Northumbrian power . In 660 , Oswiu forced Ecgfrith to marry Æthelthryth , a daughter of Anna of East Anglia . Ecgfrith was then made king of Deira in 664 after his half - brother Alhfrith , who according to Bede had rebelled against Oswiu earlier that year , disappears from history . According to the " Liber Eliensis " , “ Ecgfrith . . . for whom he ( Oswiu ) had felt a deep love , he appointed as his sharer in the kingship over the province of York ( the capital of Deira ) , since , being oppressed by bodily illness , he was finding difficulty in maintaining secure jurisdiction over the kingdom . ” Ecgfrith became king of Northumbria following his father ' s death on 15 February 670 . Bede writes , “ In the year of our Lord 670 , being the second year after Theodore arrived in England , Oswiu , king of the Northumbrians , fell sick , and died , in the fifty - eighth year of his age . He at that time bore so great affection to the Roman Apostolic usages , that he had designed , if he recovered from his sickness , to go to Rome , and there to end his days at the holy places , having asked Bishop Wilfrid , with a promise of no small gift of money , to conduct him on his journey . He died on the 15th of February , leaving his son Ecgfrith his successor . ” Upon becoming king of Northumbria , Ecgfrith put his brother Ælfwine on the throne of Deira . King of Northumbria . In 671 , at the Battle of Two Rivers , Ecgfrith put down an opportunistic rebellion by the Picts , which resulted in the Northumbrians taking control of the land between the Firth of Forth and the Tweed for the next fourteen years . Around the same time , Æthelthryth wished to leave Ecgfrith to become a nun . Bede writes , “ Though she lived with him twelve years , yet she preserved the glory of perfect virginity , as I was informed by Bishop Wilfrid , of blessed memory , of whom I inquired , because some questioned the truth thereof ; and he told me that he was an undoubted witness to her virginity , forasmuch as Ecgfrith promised to give him many lands and much money if he could persuade the queen to consent to fulfil her marriage duty , for he knew the queen loved no man more than Wilfrid himself . ” Eventually , in about 672 , Æthelthryth persuaded Ecgfrith to allow her to become a nun , and “ she entered the monastery of the Abbess Æbbe , who was aunt to King Ecgfrith , at the place called the city of Coludi ( Coldingham , Berwickshire ) , having received the veil of the religious habit from the hands of the aforesaid Bishop Wilfrid ” . A year later Æthelthryth became founding abbess of Ely . Stephen of Ripon states that “ While he ( Ecgfrith ) was on good terms with the bishop , as many will tell you , he enlarged his kingdom by many victories ; but when they quarrelled and the queen separated from him to give herself to God , the king ' s triumphs ceased ” . Stephen implies that Ecgfrith divorced Æthelthryth after his victory over Wulfhere of Mercia in 674 ( see below ) , but , evidently , they had divorced a couple of years before . At some point between 674 and 678 ( when he expelled Wilfrid from his kingdom ) , Ecgfrith married again , to Eormenburg , of whom little is known . In 674 , Ecgfrith defeated Wulfhere of Mercia , which enabled him to seize Lindsey . In 679 , he fought the Mercians again , now under Wulfhere ' s brother Æthelred ( who had married Ecgfrith ' s sister Osthryth ) , at the Battle of the Trent . Ecgfrith ' s own brother Ælfwine was killed in the battle and , following the intervention of Theodore , the Archbishop of Canterbury , Lindsey was returned to the Mercians . Coinage . Ecgfrith appears to have been the earliest Northumbrian king , and perhaps the earliest of the Anglo - Saxon rulers , to have issued the silver penny , which became the mainstay of English coinage for centuries afterwards . Coins had been produced by the Anglo - Saxons since the late 6th century , modelled on the coins being produced by the Merovingians in Francia , but these were rare , the most common being gold " scillingas " ( shillings ) or " thrymsas " . Ecgfrith ' s pennies , also known as " sceat tas " , were thick and cast in moulds , and were issued on a large scale . Raid on Ireland . In June 684 , Ecgfrith sent a raiding party to Brega in Ireland under his general Berht , which resulted in the seizing of a large number of slaves and the sacking of many churches and monasteries . The reasons for this raid are unclear , though it is known that Ecgfrith acted against the warnings of Ecgberht of Ripon and that the raid was condemned by Bede and other churchmen . Death . In 685 , against the advice of Cuthbert of Lindisfarne , Ecgfrith led a force against the Picts of Fortriu , who were led by his cousin Bridei mac Bili . The Northumbrians were lured by a feigned flight in the mountains and Ecgfrith was then slain at the Battle of Nechtansmere , located at either Dunnichen in Angus or Dunachton in Badenoch . This defeat severely weakened Northumbrian power in the north and Bede dates the beginning of the decline of the kingdom of Northumbria from Ecgfrith ' s death . He was succeeded by his illegitimate half - brother , Aldfrith . Cuthbert ' s vision . A popular legend concerning Ecgfrith ' s death at Nechtansmere has his queen , Eormenburg , touring the church at Carlisle with Cuthbert during the campaign , as she could not bear to stay behind at the royal quarters and sit patiently awaiting news of the battle ' s outcome . During the tour Cuthbert stopped , paused , and said to Eormenburg , " I have just had a vision of your husband ' s death . Return to your palace and escape with your children . " Almost immediately , a messenger arrived from the field at Nechtansmere with the news that Ecgfrith had been slain and his army routed .