Events from the 9th century in Ireland.
- 802
- Death of Muiredach mac Domnaill, King of Mide. He is succeeded by Diarmait mac Donnchado.
- 803
- 804
- 806
- Viking raid on Iona Abbey in which 68 people, the entire population of the abbey, are massacred.
- 807
- 812
- 815
- 819
- Conchobar mac Donnchada or Conchobar mac Donnchado is High King of Ireland with opposition (rí Érenn co fressabra).
- 832
- A Viking fleet of about 120 ships under Turgesius invades kingdoms on Ireland’s northern and eastern coasts.[5]
- Clondalkin was sacked by Vikings from Denmark and the monastery was burned to the ground.
- 833
- Death of Conchobar mac Donnchada, King of Mide and High King of Ireland with opposition.[6]
- 836
- Viking raids penetrate deep inland.[4]
- 837
- 838 - 841
- A small Viking fleet enters the River Liffey in eastern Ireland, probably led by the chieftain Saxolb (Soxulfr) who is killed later this year. The Vikings overwinter on Lough Neagh in 840[1] and set up a base, which the Irish call longphorts and which will eventually become Dublin.[2]
- 839
- Thorgest (in Latin Turgesius) is the first Viking to attempt creation of an Irish kingdom. He sails up the Shannon and the Bann to Armagh where he forges a realm spanning Ulster, Connacht and Meath.
- 840
- 841
- 842
- 843
- Death of Mael Ruanaid mac Dunnchado, King of Mide since 833.
- 845
- 846
- Máel Sechnaill becomes overking of the Uí Néill, reigning until his death in 862.[4]
- 847
- Death of Feidlimid mac Cremthanin, King of Munster, who has reigned since 820.[4]
- 847 or 848
- Birth of Flann Sinna (d. 916), son of Máel Sechnaill I of Clann Cholmáin, a branch of the southern Uí Néill. He is King of Mide from 877.
- 848
- Death of Fínsnechta mac Tommaltaig, King of Connacht.
- Viking army defeated by Máel Sechnaill, High King of Ireland, near modern Skreen, County Sligo.
- Viking army defeated by Tigernach mac Fócartai, King of Lagore, somewhere in modern County Sligo
- Viking army defeated by Ólchobar mac Cináeda, King of Munster, and Lorcán mac Cellaig, King of Leinster, near modern Castledermot, County Kildare. The Viking leader Tomrair is killed; he is called jarl and deputy of the king of Laithlind.
- Viking army defeated near Cashel by Ólchobar mac Cináeda.
- Vikings at Cork; besieged by Ólchobar mac Cináeda.
- The Annales Bertiniani report the arrival of Irish envoys at the court of Frankish Emperor Charles the Bald. They bring gifts from the "king of the Irish" and announced an Irish victory over Vikings. The Irish annals record several defeats for Viking armies; which of these is meant is unclear. The identity of the "king of the Irish" is no more certain, but Ólchobar mac Cináeda may be intended rather than Máel Sechnaill.
- Sedulius Scottus arrives at Liège, perhaps having been a member of the embassy to Charles the Bald.
- 851
- Máel Sechnaill mac Máele Ruanaid secures the submission of the King of Ulaid.[7]
- Cináed mac Conaing is drowned on the orders of Máel Sechnaill and Tigernach mac Fócartai.[8]
- 853
- Amlaíb, "son of the king of Laithlind", arrives in Ireland and collects tribute from the Vikings and the Irish.[9]
- 860 or 862
- Death of Mael Sechnaill I, overking of the Uí Néill, who has reigned since 846.[4]
- 864
- Death of Lorcan mac Cathail, King of Mide since 862.
- 866
Mac Annaidh, Séamas, ed. (2001). Illustrated Dictionary of Irish History. Dublin: Gill & Macmillan. ISBN 9780717135363.
Duffy, Seán (2005). The Concise History of Ireland. Dublin: Gill & Macmillan. ISBN 9780717138104.
Moody; Martin; Byrne, ed. Maps, Genealogies, Lists. p. 192, 193, n. 26.
Moody, T. W.; Martin, F. X., eds. (1967). The Course of Irish History. Cork: Mercier Press. pp. 59, 95.
Lalor, Brian, ed. (2003). The Encyclopaedia of Ireland. Dublin: Gill & Macmillan. p. 9. ISBN 0-7171-3000-2.