The missionary called Ansgar is a real historic person. In fact his is in danish history described as the person who brought christianity to Denmark. He lived almost at the same time as Charlemagne. He is here seen carrying "jernbyrd" (danish for ordeal), but it was in fact not him who did it, but a bishop later in history during king Harald Bluetooth, named Poppo, who did that to prove his christian faith to the danish king (who was not yet christian, but became that later).
The lines that King Ecbert speaks beginning at 26:15 are lines from T.S. Eliot's "Burnt Norton."