¹⁷Duffy, Seán. "Brian Boru at the Battle of Clontarf: A Medieval Version of 1916?" Irish Times. Web. 09 Apr. 2014. <http://www.irishtimes.com/culture/heritage/brian-boru-at-the-battle-of-clontarf-a-medieval-version-of-1916-1.1667155>.
The quotation "...slaughter of the Foreigners of the Western World," is from the Annals of Innisfallen, written near the end of the 11th century. According to Professor Duffy, this account of the battle "...is as close as the author of the Inisfallen entry on Clontarf comes to describing it as a victory for Brian, and it is by no means certain that he  viewed it as such. From his viewpoint— although he says it in a rather matter-of-fact way—by far the most considerable outcome of the encounter was the death of Brian." (Duffy, Seán. Brian Boru and the Battle of Clontarf. Dublin: Gill & Macmillan, 2013. 257.)