The Battle of Blain, also called the Battle of Messac, is fought on May 24, 843 by the forces of Lambert II of Nantes and Erispoe, prince of Brittany, against Renaud, Frankish Count of Nantes.
It arises from Breton resistance to Frankish power within Brittany and disputes over control of the County of Nantes.
The defeat of the Franks leads to a period of Breton expansionism.
