first bishop of Limerick died in 652, indicating the city was a place of some note. In 812 Danes sailed up the Shannon and pillaged the town, burned the monastery of Mungret but were forced to flee when the Irish attacked and killed many of their number. Viking origins The earliest record of Vikings at Limerick is in 845, reported by the Annals of Ulster, and there are intermittent reports of Vikings in the region later in the 9th century. Permanent settlement on the site of modern Limerick had begun by 922. In that year a Viking jarl or prince called Tomrair mac Ailchi—Thórir Helgason—led the Limerick fleet on raids along the River Shannon, from the lake of Lough Derg to the lake of Lough Ree, pillaging ecclesiastical settlements. Two years later, the Dublin Vikings led by Gofraid ua Ímair attacked Limerick, but were driven off. The war between Dublin and Limerick continued until 937 when the Dubliners, now led by Gofraid's son Amlaíb, captured Limerick's king Amlaíb Cenncairech and for some reason destroyed his fleet. However, no battle is actually recorded and so a traditional interpretation has been that Amlaíb mac Gofraid was actually recruiting Amlaíb of Limerick for his upcoming conflict with Athelstan of England, which would turn out be the famous Battle of Brunanburh. The 920s and 930s are regarded as the height of Norse power in Ireland and only Limerick rivalled Dublin during this time. The last Norse King of Limerick was Ivar of Limerick, who features prominently as an enemy of Mathgamain mac Cennétig and later his famous brother Brian Boru in the Cogad Gáedel re Gallaib. He and his allies were defeated by the Dál gCais, and after slaying Ivar, Brian would annex Norse Limerick and begin to make it the new capital of his kingdom. The power of the Norsemen never recovered, and they were reduced to the level of a minor clan; however, they often played pivotal parts in the endless power struggles of the next few centuries. Brian Boru's son, Donnchad (Donough), was routed by Diarmait mac Maíl na mBó, King of Leinster, in the year 1058 when Limerick was burned, a punishment he repeated five years later. A year later Diarmait defeated Donnchad again forcing him to flee overseas and installing Turlough instead. Obviously Limerick was of great importance as evidenced by being a contentious issue between neighbouring chieftains and