VIKING INCURSIONS (Medieval Ireland)

Viking incursions are first recorded in Ireland in a.d. 795. The earliest targets were churches and communities located on islands or near the coast. While surprise was an essential feature of these early hit-and-run attacks, Irish armies began to intercept the raiders, with varying degrees of success, from the 810s. By the 820s, Viking fleets had circumnavigated Ireland (for example, raiding Skellig Michael in 823). The long distance of some of these campaigns from Scandinavia has led some commentators to suggest that the first raiders came from colonies in the Northern and Western Isles of Scotland.

Viking settlements.

Viking settlements.

Initially, Vikings seem to have been motivated by desire for portable wealth in the form of tribute, stolen goods (including reliquaries—the contents were sometimes discarded), and slaves. Some of the loot made its way back to Scandinavia, as demonstrated by finds of insular metalwork in Norwegian graves.

In the 830s and 840s, Vikings made more strenuous efforts to establish a foothold in Ireland. Numerous bases, sometimes called longphoirt (ship ports), were founded. The earliest recorded examples are Arklow (836), Lough Neagh (839), and Dublin and Annagassan (841). At the same time Viking campaigns extended further inland, exploiting the major river systems of Ireland. The bases enabled booty to be ransomed or traded locally, and they fostered closer interaction between Vikings and the Irish. Many bases were temporary, but others, notably Dublin, Limerick, and Waterford, have been occupied ever since.


A number of Irish kings used this new turn of events to their advantage by recruiting Viking support against their enemies. Alliances between Vikings and Irish, such as that involving the Osraige king Cerball mac Dungaile, are well attested from the mid-ninth century. In consequence, the reasons behind Viking incursions became more sophisticated, combining desire for booty with political strategy. Of the native rulers who sought to block Viking expansion in Ireland, Mael-Sechnaill, son of Mael-ruanaid, achieved particular success.

It is evident that a number of different Viking armies operated in Ireland. During the 850s, three major groups jostled for power: Finngaill (Fair Foreigners), Dubgaill (Dark Foreigners), and Gall-Goidel (Foreign-Gaels). The Dark Foreigners were ultimately successful under the leadership of Ivarr (who died in 873) and his descendants, who were based in Dublin.

During the late ninth century there was a decrease in recorded attacks in Ireland, which may be linked with the activities of Ivarr and his associates in Britain. In 866 and 867, Ivarr’s absence encouraged Irish rulers to destroy a number of Viking bases. After a resurgence of Viking attacks in Ireland in the late 870s and 880s, the power of Ivarr’s descendants was compromised by dynastic infighting. This led to the expulsion of leading Vikings from Dublin in 902 by a coalition of troops from Leinster and Brega. The exile of the dynasty of Ivarr lasted until 914. In the interim, there is scant record of Viking activity in Ireland, while Cerball mac Muirecain, who had ousted the Viking leaders from Dublin, died in 909.

After the restoration of the dynasty of Ivarr, there was a period of vigorous Viking activity that lasted until the 940s. These years perhaps mark the zenith of Viking power in Ireland. Recurrent attacks were led against Irish power centers such as Armagh and Clonmacnoise. There was also fierce competition between the Viking settlements of Dublin and Limerick. Numerous Viking bases were established across Ireland in these years as the rival groups sought to extend their sphere of influence. These incursions were curtailed in 937, when the Vikings of Limerick were crushed by their Dublin rivals, and in the 940s by defeats inflicted on Dublin by Congalach, over king of Brega.

In the late tenth century, Viking settlements increasingly fell under the influence of Irish rulers. Not only did Viking incursions decrease in number, but their actions became less autonomous. Brian Boru brought Waterford, Limerick, and (temporarily) Dublin under his control before his death at the battle of Clontarf in 1014.

From that time, ambitious Irish over kings vied for control of the wealth and military resources of Dublin, which was the premier town of Ireland. Viking armies increasingly acted under the direction of Irish leaders. Nevertheless, the Viking dynasty of Ivarr still remained influential in Dublin. A branch of the dynasty, which ruled the Hebrides and Man, also continued to intervene in Irish affairs. In 1091, 1142, and perhaps in 1162, Viking kings of the Isles seized control of Dublin. After Magnus, king of Norway, took control of the Isles in 1098, he also intruded in Irish politics. He was killed on a raid in Ulster in 1103, and his alleged son from an Irish or Hebridean lover went on to rule Norway. Thus, for an extended period, the kingdom of the Isles was closely linked with Viking activity in Ireland.

The Viking Age in Ireland ended in the 1170s when the English seized control of the Hiberno-Scandinavian towns. In a final gasp for power, Ascall, the deposed ruler of Dublin, led a contingent from Man and the Isles against the town in 1171, but he was captured and beheaded. The term gall (foreigner), most frequently applied by Irish chroniclers to the Vikings, was soon after transferred to the English.

Viking incursions had a significant impact on Irish history. To them, past scholars have attributed both the decline of Uf Neill as over kings of Ireland and the increasing lay control of churches—although such views have since been modified. In the economic sphere, Vikings stimulated trade through their network of external contacts. They founded towns and introduced coinage. Irish rulers adopted Viking military techniques, and Vikings also made their mark on Irish art and literature. In turn, the Irish exercised a profound influence on Viking settlers. As Vikings from Ireland made incursions elsewhere, this influence extended to other colonies. Thus, Hiberno-Viking impact can be traced in diverse sources such as place names, saints cults, or medieval literature in Normandy, Iceland, and Western Britain.

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