Ecgfrith (645–May 20, 685) was the King of Northumbria from 670 until his death. He ruled over Northumbria when it was at the height of its power, but his reign ended with a disastrous defeat in which he lost his life.

Ecgfrith was the son of his predecessor as king, Oswiu of Northumbria. Bede tells us, in his Ecclesiastical History of the English People, that Ecgfrith (or Egfrid, as his name is spelled there) was held as a hostage "at the court of Queen Cynwise in the province of the Mercians" at the time of Penda of Mercia's invasion of Northumbria in 654 or 655. Penda was, however, defeated and killed by the Northumbrians under Oswiu in the Battle of Winwaed, a victory which greatly enhanced Northumbrian power.

Ecgfrith was made king of Deira, a sub-kingdom of Northumbria, in 664, and he became king of Northumbria following his father's death on February 15, 670. He had married Æthelthryth, the daughter of Anna of East Anglia, in 660; however, she took the veil shortly after Ecgfrith's accession, a step which possibly led to his long quarrel with Wilfrid, the Archbishop of York . Ecgfrith married a second wife, Eormenburg, before 678, the year in which he expelled Wilfrid from his kingdom.

Early in his reign he defeated the Picts, who had risen in revolt, and created a new sub-kingdom in the north called Lothian. In 674, Ecgfrith defeated Wulfhere of Mercia and seized Lindsey. In 679, he fought a battle against the Mercians under Æthelred (who had married Ecgfrith's sister, Osthryth) on the river Trent. Ecgfrith's brother Ælfwine was killed in the battle, and the province of Lindsey was given up when peace was restored at the intervention of Theodore of Canterbury.

In 684 Ecgfrith sent an expedition to Ireland under his general Berht, which seems to have been unsuccessful. In 685, against the advice of Cuthbert, he led a force against the Picts, who were led by his cousin Brude mac Bili , but was lured by a feigned flight into their mountain fastnesses and slain at Nechtansmere (now Dunnichen ) in Forfarshire. This disastrous defeat severely weakened Northumbrian power in the north, and Bede dates the beginning of the decline of Northumbria from Ecgfrith's death. He was succeeded by his illegitimate half-brother, Aldfrith.

See Eddius, Vita Wilfridi (Raine, Historians of Church of York, Rolls, Series, London, 1879 - 1894), 19, 20, 24, 34, 39, 44; Bede, Hist. Eccl. (Plummer, Oxford, 1896), iii. 24; iv. 5, 12, 13, 15, 19, 21, 26.

This entry was originally from the 1911 Encyclopedia Britannica.