The arrival of Turgeis[4] (O.N. Thorgestr) in Armagh, about 832, marks a new phase of the invasions. Hitherto the Vikings had come in isolated parties solely for purposes of plunder; now, however, “great sea-cast floods of foreigners” landed in every harbour, and began to form settlements in various parts of the island. Dublin was first occupied in 836, and four years later the Norsemen strengthened their position there considerably by the erection of a _longphort_ or fortress. From their _longphort_ at Linn Duachaill (between Drogheda and Dundalk) built in the same year, they made their way to the West and plundered Clonmacnois, while settlers from Cael-uisce, near Newry, went south and laid waste County Kildare.[5]
The power of Turgeis was not confined to the north of Ireland. His fleets were stationed on Loch Ree, the centre from which Meath and Connacht were devastated. His wife, Ota (O.N. Authr), desecrated the monastery of Clonmacnois by giving her oracular responses (_a frecartha_) from the high altar.[6] The tyranny of Turgeis came to an end in 845, when he was captured by Maelsechnaill, who afterwards became _árd-rí_, and was drowned in Lough Owel.[7]
After his death the tide of battle turned in favour of the Irish, and the Norsemen were defeated in several battles. Weakened by warfare, they had to contend in 849 with an enemy from without--the Dubh-Gaill[8] or Danes who had sailed round the south coast of England and landed in Ireland “to exercise authority over the foreigners who were there before them.” Two years after their arrival the newcomers plundered the fortresses at Dublin and Dundalk, but were attacked in the following year on Carlingford Loch by the Norsemen. In this great naval battle, which lasted three days and three nights, the Danes were finally victorious.[9]
“Amhlaoibh Conung, son of the King of Lochlann,” known in Icelandic sources as Olaf the White, came to Ireland about 852 to rule over his countrymen, and to exact tribute from the Irish.[10] According to the _Fragments of Annals_, he left suddenly and returned a few years later accompanied by his “younger brother, Imhar,” who may be identified with Ivarr Beinlausi (_i.e._, “the Boneless”) son of Ragnarr Lothbrók. Both kings ruled from Dublin, which town now gained a new importance as the seat of the Scandinavian Kings in Ireland. In 865 the Vikings extended their activities to Scotland, whence they carried off much plunder and many captives. An expedition on a larger scale was made by Olaf and Ivarr in 869, when Dumbarton, after a four months’ siege, fell into their hands. They returned in triumph to Ireland in the following year with a large number of English, British, and Pictish prisoners and ended their victorious march by the capture of Dunseverick (Co. Antrim).[11]