Christianity had early spread from Britain to Ireland. The labours of St. Patrick[240:3] (d. 493) and the work of St. Bridget, the "Mary of Ireland" (d. 525), have become classics. The Anglo-Saxon invasion drove many Christians to Ireland in the fifth and sixth centuries, so that by the seventh century Ireland had become the "Island of Saints" and the whole island was Christianised. Many famous monasteries were planted, and an intense missionary zeal had sent to Scotland, North Britain,[240:4] France, Germany, Switzerland, and northern Italy many representatives of the Celtic Church. In 629, Pope Honorius exhorted the Irish Church to conform to the Roman Easter day. A Celtic deputation was then sent to Rome and, upon returning home, reported in favour of the Latin system, which was adopted first in southern Ireland in 632, then in northern Ireland in 640, and by 704 was generally observed. The Norman Conquest, in 1066, made the union of Ireland with Rome as well as with England more complete; but it was left to Henry II., who conquered Ireland in 1171, to give finality to the dependence of Ireland on Rome religiously and on England politically. Christianity was planted in Scotland during the Roman period.[241:1] An Irish colony, converted by St. Patrick, settled there in the fifth century. The labours of St. Ninian (sixth cent.), the work of St. Kentigern (d. 603), and the activity of St. Columba (d. 597) completed the conversion of the country. St. Columba was a famous Irish missionary, who went to Scotland in 563, there converted the king of the Picts and founded many churches. He made his headquarters on the small island of Iona on which was planted a monastery famous as a school for missionaries, as the centre of educational activity, and as the Rome of the Celtic Church.[241:2] For centuries the Celtic Church maintained its independence in Scotland, but gradually gave way to the better organised and more aggressive Roman Church, though the Culdees were not absorbed until 1332.[241:3]