Dictionary of National Biography, 1885-1900/Ælla (d.588)
ÆLLA (d. 588), king of the Deirans, was the son of Iffa, ealdorman of the Deirans, an Anglian tribe settled in the country called in later times the East Riding of Yorkshire. On the death of Ida, the Deirans cast off the Bernician supremacy, and, in 559, Ælla was made the first Deiran king, while the descendants of Ida continued to reign in the northern kingdom. It may be that the rivalry of these two Anglian kingdoms was the determining cause of the introduction of Latin Christianity into England, by sending into slavery those Anglian youths who excited the interest of Gregory in the market at Rome. Gregory, after playing on the name of their people, asked of what tribe they were, and being told that they were of Deira, he declared that they must be delivered from wrath. Next he asked the name of their king. ‘Ælla,’ was the answer. ‘Then,’ said he, ‘Alleluia should be sung in that land.’ Ælla did not live to see this come to pass. On his death, in 588, the Bernician king Æthelric subdued Deira. The two sons of Ælla fled into exile. The younger of them, Eadwine, was destined to return and reign gloriously. A daughter of Ælla named Acha married Æthelfrith, the son and successor of Æthelric, and had several sons by him. One of these was Oswald, under whose rule both the Northumbrian kingdoms were united.
[Anglo-Saxon Chron.; Florence of Worcester; Bede, Hist. Ecc. ii. 1, iii. 6; Green, Making of England, c. 5 and 6.]