After 30 years of war between 772 and 804, Charlemagne subjugated the pagan Saxons in Northern Germany. With fire and sword, he brings the Frankish rule into the region and Christianity. With Cologne as the center of power as Archdiocese of Cologne for the next 1,000 years.
Charlemagne’s conquests in Saxony and his coronation as Roman emperor in 800 enabled the city of Cologne to transform from a peripheral city in the east of the Frankish Empire into a center of political and spiritual power. From Cologne, the newly conquered territories in northern Germany are missionized.
Theophanu – The History of Cologne
Cologne Church Province
The Church Province of Cologne (KÖLN) with its suffragan bischoprics in the 16th century: Lüttich (Liege), Utrecht, Münster, Onsabrück, Minden and up until the middle of the 9th century also Bremen. (which is not part of the Cologne Church Province anymore in this map). Sadly I havent found a more accurate map. But since this church structure existed for exactly a thousand years, it doesn’t matter if the map is from 800 or 1500.
The Frankish Empire under Charlemagne
The Saxon Wars
Conversion of the Saxons to Christianity through Charlemagne. Painted by Alphonse de Neuville in 1869.