866 – Battle of Brissarthe
During the kingship of Charles the Bald, the Danish Vikings raided across West Francia. It did not help the already troubled relationships between the king and his dukes.
To stop the duke Brittany and his alliance with the Danes, Charles sent his commander, Robert the Strong, with an army. After a siege on a church, the Vikings fought so hard to escape that the Franks had to retreat.
Though an older book, still an interesting read: Neil Price, The Vikings in Brittany. (Viking Society for Northern Research, 1989), pp 32.
936 – Death of Henry the Fowler
Henry I was Duke of Saxony before elected King of East Francia (919). He was the first ruler not of the Carolingian dynasty and laid the foundation for the Ottonian dynasty. His reign left a strong empire for his son. He was buried in Quedlinburg abbey. He is succeeded by his son, Otto the Great.
See: Find a Grave and S.H. Steinberg, A Short History of Germany, (Cambridge University Press, 1944, pp. 7)