In 690 A.D., Willibrord, an English monk from Northumbria, landed at the then mouth of the Rhine where the town of Katwijk is now situated. Together with a group of colleagues he wished to spread Christianity throughout the land of the Friesians. The Frisians lived in the coastal region stretching from the Westerschelde to near Dokkum. Their territory bordered on that of the Frankish kings, who had converted to the Christian faith a century earlier. The port town of Dorestad aan de Rijn and the settlement of Utrecht were situated on the border. This was not a permanent border, because battles regularly broke out and the border would shift as the Friesians moved slightly to the south or the Franks to the north. During a period of success, in 630 A.D. a Frankish king had built the first church in Utrecht at the place where the Dom now stands. Shortly afterwards, however, the church had been destroyed by the Frisians.
Willibrord’s predecessors had experienced that converting the heathen Frisians would be no easy task. For this reason, Willibrord first sought support. He paid several visits to the Frankish king and the Pope in Rome. The latter appointed Willbrord Archbishop of the Frisians. In 696 A.D. Willibrord settled in Utrecht. He rebuilt the church destroyed earlier by the Frisians and commissioned the building of a new church dedicated to San Salvator, or, in other words, Jesus Christ.
Subsequently, missionaries left Utrecht for the lands of the Frisians. They were successful and by the end of Willibrord’s life – he died in 739 A.D. – the new faith had the upper hand in the coastal region. In the rest of Frisian territory , however, resistance to the new faith was strong. The local nobility regarded the missionaries as accomplices of the Franks and they clung to the old ways and their gods like Wodan and Donar. It was only at the end of the eighth century A.D. that Frankish weapons finally crushed the Frisian resistance.