Ælla, the first king of Deira, died in the year 588, leaving a son, his heir, then three years of age, and an elder daughter, Acca, married to Ethelfrid, King of Bernicia, the great kingdom of Northumbria being then divided into Bernicia and Deira, both extending from sea to sea, and separated by the river Tees. Taking advantage of his brother-in-law's tender age, Ethelfrid usurped the throne of Deira, and became King of the whole of Northumbria, and the boy Eadwine was taken into exile by his friends. For many years, until he grew up to manhood, he wandered about from one refuge to another, until at last he found a safe asylum at the court of Redwald, King of the East Angles. Ethelfrid sent a demand that he should be delivered up to him, and Redwald, in reply, said to the messenger, "Tell thy master that I have promised to protect him, and will not give him up at the dictate of any King, however powerful he may be." Eventually, however, persuaded by bribes, and terrified by threats, he agreed to deliver him up. Eadwine, hearing of this, wandered forth into the forest, and, "as he sate solitary under a tree, in dumps, musing what was best to be done," a venerable stranger suddenly appeared before him, and said, "Noble Prince, thou knowest me not, but I come to tell thee that thou shalt be restored to thy kingdom, and moreover shall become Bretwalda of the Saxon Kings, if thou listenest but to those that shall be sent to thee, to teach the worship of the only true God." Eadwine, dazzled by the prospect, readily promised to do so, when the stranger placed his hand upon his head, saying, "Remember that as a sign," and vanished as mysteriously as he had appeared. On his return to the palace, he found that, at the intercession of the Queen, Redwald had withdrawn from his engagement, and was now determined to protect the fugitive to the utmost of his power. Ethelfrid, in consequence, raised an army for the invasion of East Anglia, but was met by Redwald, and a desperate battle ensued on the banks of the river Idle, in which the usurper was defeated and slain, and Eadwine proclaimed King of Northumbria. He proved himself to be an able and vigorous ruler, adding the Isles of Man and Anglesea to his dominions, and extending his territories northward to the Forth, where he built a fortress, around which a town gradually grew up, which was called Edwin's burgh--the infant Edinburgh. He raised his kingdom to a height of power it had never before attained, and in the year 624, on the death of Redwald, he attained the dignity of Bretwalda, or Supreme King of the Saxons, and President of the Heptarchian Witenagemot, whenever any such should be called together.