Brian's hard-won authority was seriously challenged in 1013 when his ally Máel Sechnaill was attacked by the Cenél nEógain king Flaithbertach Ua Néill, with the Ulstermen as his allies. This was followed by further attacks on Máel Sechnaill by the Germanic Norsemen of Dublin under their Norse king Sigtrygg Silkbeard and the Leinstermen led by Máel Mórda mac Murchada. Brian campaigned against these enemies in 1013. In 1014, Brian's armies confronted the armies of Leinster and Dublin. The resulting Battle of Clontarf saw Brian killed, his army nonetheless victorious against the Leinstermen and Norsemen. The battle is widely lauded as an instrumental moment in Irish history, and is well known in popular memory.