Æthelstan (), who had been brought up in Mercia, and he was immediately accepted as king, but not in Wessex until the following year. In 927 he conquered Northumbria and thus became the first king of all England. Mercia briefly regained a political existence separate from Wessex in 955–959, when Edgar became king of Mercia, and again in 1016, when Cnut and Edmund Ironside divided the English kingdom between themselves, with Cnut taking Mercia. Mercia maintained its separate identity as an earldom until the Norman Conquest in 1066. Mercian dialect The dialect thrived between the 8th and 13th centuries and was referred to by John Trevisa, writing in 1387: J. R. R. Tolkien is one of many scholars who have studied and promoted the Mercian dialect of Old English, and introduced various Mercian terms into his legendarium – especially in relation to the Kingdom of Rohan, otherwise known as the Mark (a name cognate with Mercia). The Mercian dialect is the basis of Tolkien's language of Rohan, and a number of its kings are given the same names as monarchs who appear in the Mercian royal genealogy, e.g. Fréawine, Fréaláf and Éomer (see List of kings of the Angles). Mercian religion The first kings of Mercia were pagans, and they resisted the encroachment of Christianity longer than other kingdoms in the Anglo-Saxon Heptarchy. Mercian rulers remained resolutely pagan until the reign of Peada in 656, although this did not prevent them joining coalitions with Christian Welsh rulers to resist Northumbria. The first appearance of Christianity in Mercia, however, had come at least thirty years earlier, following the Battle of Cirencester of 628, when Penda incorporated the formerly West Saxon territories of Hwicce into his kingdom. The conversion of Mercia to Christianity occurred in the latter part of the 7th century, and by the time of Penda's defeat and death, Mercia was largely surrounded by Christian states. Diuma, an Irish monk and one of Oswiu's missionaries, was subsequently ordained a bishop – the first to operate in Mercia. Christianity finally gained a foothold in Mercia when Oswiu supported Peada as sub-king of the Middle Angles, requiring him to marry Oswiu's daughter, Alchflaed, and to accept her religion. Decisive steps to Christianise Mercia were taken by Chad (Latinised by Bede as Ceadda), the fifth bishop to operate in Mercia. This controversial figure was given land by King Wulfhere to build a monastery