Thorkil or Turgesius
Thorkil, or Turgesius, a Scandinavian chieftain who held sway in Ireland from about 832 to 845. It has been suggested by some writers that he was identical with Ragnar Lodbrok. He arrived with three fleets. Dr. Todd says: "He seems to have had in view a higher object than the mere plunder which influenced former depredators of his nation. He aimed at the establishment of a regular government or monarchy over his countrymen in Ireland, the foundation of a permanent colony, and the subjugation or extermination of the native chieftains. For this purpose the forces under his command, or in connexion with him, were skilfully posted on Lough Ree, at Limerick, Dundalk Bay, Carlingford, Lough Neagh, and Dublin. He appears also to have attempted the establishment of the national heathenism of his own country, in the place of the Christianity which he found in Ireland... With this view he placed his wife, Ota, at Clonmacnoise, at that time second only to Armagh in ecclesiastical importance, who gave her audiences, or according to another reading, her oracular answers, from the high altar of the principal church of the monastery." He was reinforced from time to time by the arrival of contingents of his countrymen, but in 845 was arrested in his victorious course by Malachy I., then King of Meath, who had him drowned in Lough Owel. The romantic story of his death, told by Cambrensis, evidently an imitation of the story of Hengist's treacherous banquet to Vortigern, although repeated by Keating, is not found in any ancient Irish authority.
Sources
144. Gaedhil with the Gaill, Wars of the, or the Invasions of Ireland by the Danes: Rev. James H. Todd, D.D. (Master of the Rolls Series.) London, 1867.