The movement towards Christianity began again in the late sixth and seventh centuries, helped by the conversion of the Franks in Northern France, who carried considerable influence in England. Pope Gregory I sent a team of missionaries to convert King Æthelberht of Kent and his household, starting the process of converting Kent. Augustine became the first Archbishop of Canterbury and started to build new churches across the South-East, reusing existing pagan shrines. Oswald and Oswiu, kings of Northumbria, were converted in the 630s and 640s by Scottish missionaries, and the wave of change carried on through the middle of the seventh century across the kingdoms of Mercia, the South Saxons and the Isle of Wight. The process was largely complete by the end of the seventh century, but left a confusing and disparate array of local practices and religious ceremonies. This new Christianity reflected the existing military culture of the Anglo-Saxons: as kings began to convert in the sixth and seventh centuries, conversion began to be used as a justification for war against the remaining pagan kingdoms, for example, while Christian saints were imbued with martial properties. The Council of Hertford in 673 was the first meeting of bishops from across England; it established a hierarchy in England and confirmed the observance of the traditions of the Latin Church over those of the Celtic Church, which had previously held influence in the north and west.