In the year 853, Ivar and Olaf arrived in Ireland with a large fleet and an army powerful enough to collect tribute and hostages from other Vikings and the Irish. They secured the loyalty of the Norwegian settlements, especially Dublin and Woodstown in County Waterford.
Ivar, known as ‘the Boneless’, established a dynasty that would change the course of Irish history. All of the leaders of the Viking bases at both Dublin and Waterford in the 9th and well into the 10th century were descendants of Ivar, including Reginald, the first king of Waterford and York.
With his power base at Dublin, Ivar challenged the authority of the most powerful Irish kings. He was also one of those who raided the prehistoric tombs of the Boyne Valley, Newgrange, Knowth and Dowth, which were then 4,000 years old; the first time that this had been done.
Ivar and his associates participated in the Viking conquest of East Anglia, Mercia and Northumbria, including the city of York, paving the way for the large-scale settlement of areas of eastern England by people from Scandinavia.
This was the high point of Viking rule. They had created a sea kingdom based around the Irish Sea with both Dublin and York as its seats of power.