The Battle of Cathair Cuan refers to a perhaps extended conflict fought in or between 977 and 978, or simply to a single battle in one or the other year, in Munster in Ireland. Attacking were Brian Bóruma and the Dál gCais, while defending were Donnubán mac Cathail and the remainder of the Viking army of Limerick. The latter were probably the followers of the newly elected and final King of the Foreigners of Munster Harald Ivarsson, son of the recently slain Ivar of Limerick, although it is possible Donnubán was in overall command.