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Gaelic British Isles & Ireland

Tribes and States of Ireland


Viking Kingdom of Dublin / Dyflin

The village of Dubh Linn (in Old Irish) can be dated to the pre-Roman prehistoric era in Ireland. A monastic centre also developed nearby, within the province (and kingdom) of Leinster. In 840-841 the entire area was invaded by Norsemen from Scandinavia. They established a fledgling settlement, picking up the name from the locals as Dyflin or Dyflyn, somewhere near the confluence of the rivers Poddle and Liffey. It was this that became the heart of the Viking settlement, and it developed to become the later capital of Ireland. The area formed a dark pool or dubh linn which provided a safe harbour for Viking longships, although the pool itself was filled in during the eighteenth century when Dublin was being expanded into a city. The Castle Garden within the castle grounds marks its location.

The Viking or Norse kingdom of Dublin was repeatedly attacked by the Irish kings, and it was even expelled between 902-917, but the fight to destroy the power of the Vikings in Ireland would be a long and hard one. It was probably made even harder by the fact that the Viking rulers often shared the 'throne', ensuring that there was always a leader on hand in case of difficulty. Many Dublin kings of the tenth century also held power in the Scandinavian kingdom of York, and Dublin provided one end of an extensive Scandinavian trade network that linked many other kingdoms together such as those of Orkney, Man, and the Hebrides.

(Information by Peter Kessler, with additional information from Dublin - The Making of a Capital City, David Dickson (Profile Books, 2014), from A Short History of Ireland, John O'Beirne Ranelagh (Cambridge University Press, 2001), from Gesta Danorum: The History of the Danes, Karsten Friis-Jensen & Peter Fisher (Ed & Trans), from The Makers of Scotland: Picts, Romans, Gaels and Vikings, Tim Clarkson (EPUB, 2012), from A New History of Ireland, Vol 1: Prehistoric and Early Ireland, D Ó Cróinín (Ed, 2005), from the Annals of the Four Masters, author unknown, from The Chronology of the Irish Annals, Daniel P McCarthy, and from External Links: Ireland's History in Maps, and English-Old Gaelic Dictionary, and Annals of Ulster.)

840 - 841

The Vikings set up their settlement as a longphort or ship camp of extremely large proportions. Their early history is sparsely recorded, and is largely a case of mounting raids and hoping not to be caught by the Irish kings. Their luck runs out when they are indeed caught by the Irish at Mag Itha in 845.

Viking helmet

839 - 845

Thorgest / Turgesius / Tuirgeis

First Viking ruler of Dublin. Drowned in Lough Owel.

845 - 853

Later in the same year the Vikings are dealt a heavy defeat at Mag Itha by High King Niall Caille mac Aedo Oirdnide. A further blow is the death of Thorgest which is recorded in the Annals of Ulster. He is captured by Máel Sechnaill mac Máele Ruanaid, king of Mide and soon-to-be high king of Ireland himself, and is drowned in Lough Owel.

The Viking settlement at Dubh Linn may be abandoned until 853, or perhaps used only as a seasonal base. Some Vikings may return to Norway to found the kingdom of Vingulmark, which bears traces in its very name of their stay in Ireland.

853 - 873

Ivarr the Boneless

King of the Northmen of all Ireland & Britain.

853 - 871

Olaf the White

Arrived with Ivarr. m Aud dau of Ketill Bjornsson of Man.


Viking raids into Wales are dealt a major blow when Rhodri, king of Gwynedd, defeats a major raid by Orme. The Viking leader is killed, and the Dublin Vikings are kept out of northern Wales.

865 - 870

FeatureIvarr the Boneless and his brothers are the founders of the Uí Ímair in Ireland - the clan or descendants of Ivarr. They are the sons of Ragnarr Lothbrok of Denmark, and they lead the first Viking army to invade mainland Britain in search of conquest rather than pillage. Landing in East Anglia, they ravage the kingdom for a year before heading into Northumbria in 866. That kingdom falls in 867 and a puppet king is installed. The Great Army moves south, campaigning during the spring and summer. East Anglia falls in 869, and the capital of Alt Clut is sacked in 870, with Olaf's help. Ynys Manau also falls to them around 870, and between 870-871, Ivarr's brother, Bagsecg, is involved in the attacks, leading the Great Summer Army into England and adding his forces to those of Ivarr and Halfdan.

Bagsecg is killed at the Battle of Ashdown in Wessex in 871, after which Olaf returns to Norway, and the following year the Great Army is back in Northumbria. It winters in late 872 and early 873 at Torksey on the River Trent in Lindsey, before moving west into Mercia, which is defeated in 874 and a vassal king is installed on its throne. Later that year the army divides, with one half going to Cambridge and the rest heading towards the Tyne and eventually settling in York.

873 - 883


Brother of Ivarr the Boneless. King in York (878-883).

873 - 875

Eystein Olafsson

Co-ruler while Halfdan was campaigning in Mercia.

874 - 877

Halfdan continues his family's conquering ways by seizing the kingdom of Mercia, although much of it submits to the protection of Wessex. In 877 Halfdan is expelled from the Scandinavian kingdom of York, where he had been its first Viking king. However, he may remain the acknowledged ruler of York until his death, as no one else claims the title.

Vikings in combat
This may be a fairly typical image of Vikings staging a raid - whether in Ireland or Britain the scene would have been very much the same - but they seem to be faced with some well-armed opposition on the shore

875 - 881


Co-ruler while Halfdan was in York or campaigning.

881 - 883

Mac Auisle

Co-ruler while Halfdan was campaigning. Murdered.


Eoloir Jarnknesson

Usurper. Ruled for a few months?

883? - 888

Sichfrith Ivarsson

Possibly a son of Ivarr the Boneless. Assassinated.

888 - 893

Sigtrygg (Sitric) Ivarsson

Possible brother and assassin.


Áed mac Conchobair, king of Connacht, has already met his death fighting the Vikings in support of High King Flann Sionna mac Máele Sechnaill O'Néill of Ireland. The annals now record that the men of North Connacht - specifically the Uí Amalgada, a branch of the Uí Fiachrach - defeat Norse forces and slay their leader. That leader seems not to be one of the more senior of their number, however.

893 - 894

Sichfrith Jarl

Possibly the Siefred of York (895). Probably deposed.

893 - 902

Ivar (II)

Probably subservient to Sigtrygg. Killed raiding.

894 - 896

Sigtrygg (Sitric) Ivarsson

Second time in power. Defeated and deposed.

900 - 902

FeatureThe Vikings control Ynys Manau, but they lose the island to York in the same year in which the combined forces of Laigin and Brega expel them from Ireland. Ivar returns to raiding, where he is killed by the Picts of Fortriu in 904. The Vikings are left searching for a new base of operations, which they find in 907 when Æthelred and Æthelflaed of Mercia re-found the city of Chester and settle a Viking army on the Wirral to guard the approach. More Vikings arrive along the Mersey, setting up further colonies and creating the origins of Liverpool (see feature link, right).

Viking ship
A recreation of a Viking ship of this period which was uncovered on England's west coast, in Liverpool on the Wirral peninsula in 2007

914 - 917

Sihtric and Ragnald, both descendants of Ivarr the Boneless, are active in the Irish Sea from 914. Ragnald defeats Barid son of Ottar off the coast of Ynys Manau in that year. In 917 they lead separate fleets in an attack on Ireland and while Ragnald is initially defeated by High King Niall Glúndubh, Sihtric turns the tables and defeats the high king's army. The Vikings resettle Dublin and re-found their kingdom.

917 - 921

Sihtric Caoch (the Blind)

Grandson of Ivarr. King in York (921-927).

917 - 921

Ragnald I / Ragnall

Grandson of Ivarr. Also king in York (919-921).


Ragnald seizes control of York, destroying the slow Anglo-Saxon recovery of the region. He is succeeded there by Sihtric Caoch in 921. Sihtric goes on to marry, Edith, the sister of Æthelstan of Wessex and accept baptism.

921 - 927


Brother. King in York (927).


Upon the death of Sihtric Caoch in York, Æthelstan of Wessex invades Northumbria and secures control of it with the support of the high reeves of Bamburgh, expelling the hopeful claimant, Olaf son of Guthfrith. The West Saxon king rules York as part of a united England until his death on 27 October 939.

927 - 942

Olaf / Anlaf I Guthfrithson / Amblaib

Son of Guthfrith. Claimant & king in York (927 & 940-942).

940 - 944


Brother and regent while Olaf was in York. Driven out (944)

934 - 937

The grand alliance including the Scots, Northumbrian Danes at York, Dublin Danes, and the Welsh of Gwynedd and Cumbria, mass their forces north of the Humber in a bold attempt to destroy Æthelstan of Wessex. The plan fails, however, when the West Saxons and Mercians of the south destroy the alliance at the Battle of Brunanburh in 937.

This illustration of King Æthelstan, king of all Britain as proclaimed by various charters and coins of his reign, comes from the Abbreviatio Chronicorum Angliae - he was the first English monarch to be portrayed wearing a crown

c.942 - c.972

The Vikings control Ynys Manau, but by this time the once-powerful kingdom of Dublin has been reduced to a minor player in Irish politics. Even its ruler, Sigtrygg, is unknown outside of a mention in the Annals of Ulster which itself has been suggested as being a later invention. Blácaire is still clearly in charge in 944, so he is probably the dominant king in 942-943 too.

942 - 943

Sigtrygg / Sitric

Mentioned in Annals of Ulster. Otherwise unknown.


Dublin is sacked by High King Congalach Cnogba, adding to the weakened kingdom's woes. Olaf drives out Blácaire and takes sole control, perhaps aided by his alliance with Congalach.

945 - 947

Olaf / Anlaf II Sihtricson (Cuaran)

Son of Sihtric. King in York three times (between 942-952).

947 - 948


Restored after Olaf is killed in battle. Also killed in battle.

948 - 951

Gofraid mac Sitriuc

Brother of Olaf II. Died during plague outbreak.



Claimant for the throne at York. Briefly recognised.

952 - 980

Olaf / Anlaf II Sihtricson (Cuaran)

Restored. Defeated by the Irish at the Battle of Tara.


Ireland's High King Máel Sechnaill conquers Dublin following a great victory at the Battle of Tara and a three day siege of Dublin itself, the first time the Irish kings manage to achieve such a conquest. Olaf's heir, Reginald, had also been killed at Tara, leaving the settlement without a recognised leader. As a result of the imposition of Irish overlordship, some Irish date the founding of Dublin to this year (or 988), despite its ancient heritage. Olaf abdicates and retires to Iona where he probably becomes a monk. Máel appoints his half-brother, Glúniairn, to rule the Viking kingdom.

980 - 989

Glúniairn / Járnkné

Son. Half-brother to High King Máel Sechnaill by his mother.


Glúniairn is killed, apparently by his own slave when he is drunk, although the death is more likely to be the result of factional in-fighting in Dublin. High King Máel Sechnaill descends on the kingdom and installs Sitric Silkbeard, another son of Olaf, as king.

989 - 1036

Sigtrygg / Sitric Silkbeard Olafsson

Half-brother. Irish vassal.


In a bloodless coup, High King Máel Sechnaill is dethroned by Brian Bóruma (more popularly known as Brian Boru). It results from the failure of the Northern Uí Neill, nominally Máel's kin, to support him against the military aspirations of this king of the Dál gCais of Thomond and also of Munster, who has effectively ruled the southern half of Ireland since an agreement of 997. As a result of the sudden shift in power, Viking Dublin, never entirely conquered, fights back against Irish dominance.


High King Brian Boru defeats the Dublin Norse at the Battle of Clontarf, but dies in the process. A great many other Irish nobles also die in the battle, destroying decades of hard-won Irish unity. The Uí Dúnlainge of Laigin are amongst those defeated at Clontarf, and with their usual supporters already declining - the Clann Cholmáin of Mide - their rivals in Laigin, the Uí Cheinnselaig, are able to return from relative obscurity and contest the throne there.

Battle of Clontarf
The Battle of Clontarf was a tactical disaster for the Irish, destroying hard-won unity in the face of the Viking threat that would not be repaired in time to fight off the Normans

More broadly, Máel Sechnaill is able to regain the titular high kingship with the support of his kinsman, Flaithbertach ua Néill, king of Ailech, but Ireland remains fragmented.

1034? - 1038

Towards the end of what would seem to be an unusually long period of peace for Dublin and its ruler, the kingdom is known to govern Ynys Manau during this period. This possibly starts in 1034, upon the death of Swein Kennethson, the sub-king of Manau under the overlordship of Orkney.

1036 - 1038

Echmarcach mac Ragnaill

Later King Margad MacRagnald of Ynys Manau (1052-1061).

1038 - 1046

Ivar (III) Haraldsson

Seized power. Son of Prince Harald (killed 999). Expelled.

1046 - 1052

Echmarcach mac Ragnaill

Restored. Ally of High King Donnchad mac Brian.


High King Donnchad mac Brian's main rivals are Diarmait mac Maíl na mBó, king of Laigin and his ally, Niall mac Eochada, king of Ulaid, plus Áed in Gaí Bernaig, king of Connacht. Diarmait now installs his son Murchad as king of Dublin, expelling Donnchad's brother-in-law and ally, Echmarcach mac Ragnaill. The opposition to Donnchad grows so that he is deposed in 1063 and goes on pilgrimage to Rome where he dies the following year.

1052 - 1070

Murchad mac Diarmata mac Mael na mBo

Also King Murchaid MacDairmit of Ynys Manau (1061-1070).

1070 - 1072

Diarmait mac Mail na mBo

High King (1064-1072), and king of Leinster & Dublin.

1070 - 1072

Domnall mac Murchada mac Diarmata

Son of Murchad and co-ruler.

1070 - 1072

Gofraid mac Amlaib mac Ragnaill

Co-ruler. Reinstalled in 1072?

1072 - 1074?

Toirdelbach Ua Briain

High King (1072-1086), and king of Munster.


Upon the death of High King Diarmait mac Máil na mBó in battle, his close ally Toirdelbach O'Brien succeeds him. His first act is to ravage Osraige and Laigin, during which he burns Uí Cheinnselaig and takes a good deal of booty and cows, along with hostages. The Vikings of Dublin, generally known in the annals as 'the foreigners', give him the kingship of their settlement.

In the following year, Conchobar Ua Máel Shechnaill, king of Mide, is murdered and Toirdelbach ravages the now-unprotected Irish midlands. This is followed by a visit to Connacht from which he extracts more hostages, both from the Uí Conchobair and the Uí Ruairc. Laigin is divided between rivals, ending its short-term threat to his power, and Gofraid mac Amlaíb meic Ragnaill is installed in Dublin as his sub-king (or reinstalled - the dates for Gofraid seem to be confused).

1072 - 1074

Gofraid mac Amlaib mac Ragnaill

Sub-king. Banished from Dublin.

1074 - 1086

Muirchertach Ua Briain

Son of Toirdelbach Ua Briain. High King, and king of Munster.

1086 - 1089

Enna mac Diarmata mac Mael na mBo

Heavily involved in Laigin's leadership.


Donnchad mac Domnail Remair

Brother and co-ruler. King of Laigin. Killed.

1087 - 1094

The Annals of Ulster record that the grandsons of Ragnall, the kings of Dublin, are killed on an expedition to attack Ynys Manau. The ruler of Manau, Godred Crovan, in turn invades Dublin and takes the kingship until he too is kicked out.

A Viking longboat
The attack and conquest of Dublin by Godred Crovan would have been launched from longboats just like this

1089 - 1093

Viking problems don't end there. As high king, Muirchertach stamps his authority over Ireland by engaging in forays into Mide and Laigin in 1089. He seizes the kingship of Laigin and attacks the Vikings of Dublin. In 1093, he accepts the submission of Domnall mac Flainn Ua Maíl Shechnaill, king of Mide, while Godred Crovan of Dublin is banished.

aft.1091 - 1094

Godred Crovan / Gofraid Crobán

Also King Godred IV of Ynys Manau (1079-1095). Banished.

c.1094 - 1102

Domnall mac Muirchertaig ua Briain

Of the Uí Briain of Munster.

1102 - 1103

Magnus III the Barefoot / Barelegs

King of Norway, and Ynys Manau (1095-1102). Killed.

1103 - ?

Domnall mac Muirchertaig ua Briain

Of the Uí Briain of Munster. Restored.


Donnchad mac Murchada, king of Laigin, and Conchobar mac Congalaig (also referred to as Conchobar Ua Conchobair Failge), king of the Uí Failghe and joint king of Laigin, see an opportunity to make the most of the faltering power of Munster - under the power of the Uí Briain. The pair launch an attack on Dublin, whose defending forces are led by Domnall mac Muirchertaig ua Briain (Domnall Gerrlámhach) of the Uí Briain (dies 1135). The attempted invasion is defeated and both kings are killed, but Donnchad's successor is soon able to seize Dublin for Laigin.


Donnchad mac Murchada mac Diarmata

Joint king of Laigin. Briefly a claimant for Dublin's throne.

1115 - 1117

Diarmait mac Énna meic Murchada

King of Laigin. Died in Dublin.


Enna mac Donnchada mac Murchada

King of Laigin. Expelled by Domnall Gerrlámhach.


With the death of Diarmait mac Énna meic Murchada in Dublin, his successor and kinsman, Enna, is expelled by Domnall mac Muirchertaig ua Briain (Domnall Gerrlámhach). The Uí Briain of Munster now control the stronghold once again.

1117 - ?

Domnall mac Muirchertaig ua Briain

Of the Uí Briain of Munster. Restored for a second time.


An army is formed by Tiorrdelbach Ua Conchobhair, so he gives the vassal kingdoms of Dublin and Laigin to his own son, Conchobair. Then he marches south to defeat Cormac Mac Carthaigh in battle, before burning his camp at Sliabh-un-Caithligh.

1126 - 1127

Conchobair mac Tiorrdelbach

Son of Tiorrdelbach Ua Conchobair. Killed 1144.


There is now a gap in the available information about the kings of Dublin. It could be the case that it is drawn directly under Laigin's control during the lifetime of Conchobair mac Tiorrdelbach. As usual in Dublin, when a ruler is next known he is from a different house.

? - 1133


Forced to flee Ireland.


A Norman attack from England forces Thorkell to flee Dublin and Ireland altogether for the safety of the Scottish Highlands. However, there seems to be limited information available about this period, so the circumstances surrounding the attack and its presumed failure are unclear. Do the Normans control Dublin for a time or is an Irish vassal ruler reinstalled?

The coming of the Normans to Ireland was a blow for the Irish (and the Norse!) - the newcomers were tactically and militarily far more powerful than anything seen before by the native kings

1141 - 1142

Conchobair Ua Briain

Son of Diarmait Ua Briain. King of Munster. Died.

1142 - 1148

Ottar of Dublin

A powerful Norse landowner in the Hebrides. Murdered.

? - 1146

Ragnall Thorgillsson

Son of Thorkell and co-ruler.

1146 - 1160

Brotar Thorgillsson


1160 - 1171

Hasculf Thorgillsson

Brother. Killed by Normans in 1171. The Dublin kingdom ends.

1169 - 1171

The Normans of England invade Ireland, and Viking Dublin and Waterford are conquered, never to regain independence. Hasculf Thorgillsson attempts to regain it by force but is killed in the process. The settlement is used as the main base for the expansion of the English conquest, becoming the capital of the entire country, and remaining so even after southern and central Ireland achieve independence.

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