TheBattle of Islandbridge, also called theBattle of Áth Cliath, took place on 14 September 919, between a coalition of nativeIrish, led byNiall Glúndub, overking of theNorthern Uí Néill andHigh King of Ireland, and the Dublin-basedVikings of theUí Ímair, led bySitric Cáech. It was one in a series of battles initiated by the native Irish to attempt to drive the Vikings of the Uí Ímair from Ireland. The battle was a decisive victory for Sitric Cáech and the Uí Ímair, with Niall Glúndub and five other Irish kings dying in the battle.

The rulingVikings ofDublin, theUí Ímair, had been expelled from the city in 902 by a joint force led by Máel Finnia mac Flannacán, overking ofBrega andCerball mac Muirecáin, overking ofLeinster.^[1] However, this expulsion was temporary and Viking raids continued on Irish settlements. In 914 a large Viking fleet sailed to the previously Viking-controlled city ofWaterford, and the following year more Vikings settled inLimerick, though Dublin itself remained outside Uí Ímair control.^[2]

In 917 two prominent members of the Uí Ímair,Ragnall andSitric Cáech, grandsons ofÍmar, sailed separate fleets to Ireland, Ragnall landing at Waterford and Sitric Cáech landing at "Cenn Fuait" inLeinster.

The exact location of "Cenn Fuait" is uncertain. TheAnnals of Ulster describe Cenn Fuait as being on theairer of Leinster.Airer is an Irish word meaning "coast" or "border region". Suggestions for the location include Confey near modern-dayLeixlip,County Kildare andSt Mullin's,County Carlow.^{[nb 1][4]}

Several native Irish kings gathered forces to try to drive off the Vikings, includingNiall Glúndub, over-king of the NorthernUí Néill andHigh King of Ireland, andAugaire mac Ailella, over-king of Leinster. The Vikings fought and won a victory against Niall Glúndub and the men of the Uí Néill at theBattle of Mag Femen inBrega, and then wonanother victory against Augaire mac Ailella and the men of Leinster at Cenn Fuait.^{[nb 2][6][7]} Sitric led his men on a triumphant return toDublin, re-establishing Viking rule and installing himself as king, while Ragnall returned to England.^[4]

In 919 a number of Irish kings banded together to try to expel the Vikings from Dublin once more. The known kings who took part in this coalition were Niall Glúndub of theNorthern Uí Néill, Áed mac Eochocáin ofUlster, Máel Mithig mac Flannacain ofBrega, Mael Craibe mac Duibsinig ofAirgíalla, Conchobar mac Flainn ofMide, and Cellach mac Fogartaig of South Brega.^[8] The historianClare Downham has suggested that Niall Glundub and the other kings were emboldened by the departure of Ragnall from Ireland to try again to force out the Uí Ímair.^[9] The forces of Sitric and Niall met nearIslandbridge in modern dayCounty Dublin on the fourteenth of September.^{[nb 3][10]} TheAnnals of the Four Masters describe Niall's words before the battle:

Whoever wishes for a speckled boss, and a sword of sore-inflicting wounds, and a green javelin for wounding wretches, let him go early in the morning to Áth Cliath.^[11]

The battle was an overwhelming victory for the Vikings, with many Irish nobles killed, including six kings:^[12] Niall Glúndub of the Northern Uí Néill, Áed mac Eochocáin ofUlster, Máel Mithig mac Flannacain ofBrega, Mael Craibe mac Duibsinig ofAirgíalla, Conchobar mac Flainn ofMide, and Cellach mac Fogartaig of South Brega.^{[8][nb 4]} Other notable casualties include one of Niall Glúndub's kinsmen, a member of the ruling dynasty of theSouthern Uí Néill, and Eiremón mac Cennétig, Chief of theCenél Maine.^[14]

The failure of this coalition to drive out the Vikings ensured the hold of the Uí Ímair on Dublin remained strong. Nevertheless, war between the Vikings and the native Irish continued, and the following year there was a battle between the Vikings of Dublin andDonnchad Donn, the brother of the slain king Conchobar mac Flainn and the new High King of Ireland.^[9]

53°20′50″N6°18′30″W / 53.3473°N 6.3083°W /53.3473; -6.3083

• "Annals of the Four Masters".Corpus of Electronic Texts.University College Cork. 16 December 2013. Retrieved5 March 2015.
• "Annals of Ulster".Corpus of Electronic Texts.University College Cork. 15 August 2012. Retrieved5 March 2015.
• "Chronicon Scotorum".Corpus of Electronic Texts (24 March 2010 ed.).University College Cork. 2010. Retrieved26 November 2014.
• "Dictionary of the Irish Language".Electronic Dictionary of the Irish Language (2012 ed.).Royal Irish Academy. 2012. Archived fromthe original on 2 January 2015. Retrieved5 March 2015.
• "Fragmentary Annals of Ireland".Corpus of Electronic Texts (5 September 2008 ed.).University College Cork. 2008. Retrieved5 March 2015.
• Murphy, D, ed. (1896).The Annals of Clonmacnoise. Dublin:Royal Society of Antiquaries of Ireland. Accessed viaInternet Archive.
• Todd, JH, ed. (1867).Cogad Gaedel re Gallaib: The War of the Gaedhil with the Gaill. London:Longmans, Green, Reader, and Dyer. Accessed viaInternet Archive.

• Bartlett, Thomas; Jeffery, Keith (1997).A Military History of Ireland. Cambridge University Press.ISBN 978-0-521-62989-8.
• Downham, Clare (2007).Viking Kings of Britain and Ireland: The Dynasty of Ívarr to A.D. 1014. Edinburgh:Dunedin Academic Press.ISBN 978-1-903765-89-0.
• Duffy, Seán (2005).Medieval Ireland: An Encyclopedia. Routledge.ISBN 978-1-135-94824-5.
• Forte, Angelo; Oram, Richard D.; Pedersen, Frederik (2005).Viking Empires. Cambridge University Press.ISBN 978-0-521-82992-2.
• Sawyer, Peter (2001).The Oxford Illustrated History of the Vikings. Oxford University Press.ISBN 978-0-19-285434-6.

• CELT: Corpus of Electronic Texts atUniversity College Cork. TheCorpus of Electronic Texts includes theAnnals of Ulster andthe Four Masters, theChronicon Scotorum and theBook of Leinster as well as Genealogies, and various Saints' Lives. Most are translated into English, or translations are in progress.

• 910s conflicts
• Battles involving the Vikings
• Battles involving the Uí Néill
• History of County Dublin
• Viking Age in Ireland

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