The settlement was first mentioned about 780 when Charlemagne in course of the Saxon Wars crossed the Oker river and had a church dedicated to Saint Stephen erected at a place then called "Salingenstede". This church became a centre of the Christian mission among the pagan Saxons, overseen by Hildegrim of Châlons, and the origin of the later Bishopric of Halberstadt. On 1 April 974, Emperor Otto II issued a deed granting market and mint rights to "Seligenstadt", this is commonly regarded as the date of the town's foundation.