The conversion began in 597 with the mission Gregory the Great sent to Kent under Augustine, and proceeded kingdom by kingdom, with reversions, across most of a century. Irish missionaries working from Iona converted Northumbria from the north, and the Synod of Whitby in 664 decided in favour of Roman practice on the dating of Easter, which settled the question of which church the English kingdoms belonged to.
Bede, writing at Jarrow by 731, is the source for nearly all of this, and his history is a work of argument as well as of record. His account of the sparrow flying through the lighted hall, offered in a Northumbrian king's council as a reason to accept the new teaching, is the most quoted description of a conversion in English.
What followed was one of the earliest vernacular Christian literatures in Europe. Caedmon's hymn, the Dream of the Rood in which the cross itself speaks as a retainer, and the biblical poems collected among the Anglo-Saxon minor poems were composed in the alliterative verse of the older tradition. Beowulf, a poem about pagan heroes written by a Christian, sits exactly on the seam. Old English became a language of preaching, of law and of scripture translation, unusually early and unusually fully.