891 - Siegfred and Gudefred died in battle

France
On the 2nd of May a viking army laid a siege at Saint-Omer ,but the viking did not have any success and later in the spring joined the forces at Noyon. On June the 25th vikings made Arnulf of Karnten suffer a defeat near the river Geule, near Maastricht.
Belgium
In the autumn the vikings made a camp near Leuven near the Dijle river.
On the 1st of September Arnulf of Karnten won a bloody battle, both Sigfred and Gudefred was killed. And chronicles told that the bodies of dead vikings blocked the run of the river.
Helge succeeded Sigfred as Danish king

Arnulf  then built a castle on a small island in the Dijle River and according to a legend the Leuven flag red-white-red colors depict the bloodstained shores of the river Dijle after the Battle of Leuven.

Franks did not manage to drive the vikings out, they stayed at the Dyle river area. A defeat and two dead leaders, did not scare them or crush the morale. But after this defeat, the Vikings never became as powerful than in the previous years.

References :Annales Fuldenses and Anglo-Saxon Chronicle