867 King Osbrtyth and Aella tried to recapture York

King Osbrtyth and Aella agreed to stop the internal struggle and join forces to defend against vikings. In the Easter 867 they tried to recapture York, but the attack broke down and both Osbryth and Aella was killed, After their victory the viking army entered Mercia and made a winter camp in Nottingham.
Treaty of Compiègne in August 867,  Charles the Bald gave Cotentin to King Salomon of Brittany. Though not specified in the treaty, the Avranchin, including Mont Saint-Michel, was likely included in the concession.
A force led by the king of Loígis Cennétig mac Gaíthéne burned the fortress at Clondalkin and killed 100 of Amlaíb's followers
An unknown site was destroyed by king of Ui Bairrche tire and according to Irish chronicles a Viking camp was build at Cork and Dun Mainne(county Kerry).
Photios claimed that he had succeeded in converting the Rus