William Longsword of Normandy was ambushed and assassinated by supporters of Arnulf I, Count of Flanders, while both were at a peace conference to settle their differences.

William Longsword was the second ruler of Normandy, from 927 until his assassination in 942.

Normandy is a geographical and cultural region in northwestern Europe, roughly coextensive with the historical Duchy of Normandy.

Arnulf I, called "the Great", was the first Count of Flanders.