Editing Olaf Guthfrithson (section)

==Biography==
Olaf first conclusively appears in contemporary records in 933 when the annals describe him plundering [[Armagh]] on 10 November.<ref name="Hudson2004">[[#Hudson2004|Hudson (2004)]]</ref> He is then recorded as allying with Matudán mac Áeda, [[List of kings of Ulster|overking of Ulaid]] and raiding as far as [[Sliabh Beagh]], where they were met by an army led by [[Muirchertach mac Néill]] of [[Ailech]], and lost 240 men in the ensuing battle along with much of their plunder.{{#tag:ref|The number of casualties given here is that given by the ''[[Annals of the Four Masters]]'' and the ''[[Chronicon Scotorum]]''. The ''[[Annals of Clonmacnoise]]'' provide the alternative number of 1200.<ref>[[#A4M|Annals of the Four Masters]], s.a. 933</ref><ref>[[#CS|Chronicon Scotorum]], s.a. 933</ref><ref>[[#AClon|Murphy (1896)]], pp. 149–150</ref>|group="nb"}} An earlier reference to a "son of Gofraid" who plundered the monastery at [[Kildare]] in 928 might refer to Olaf but no name is given.<ref name="D243244">[[#Downham|Downham (2007)]], pp. 243–244</ref> Olaf's father [[Gofraid ua Ímair]], [[Kingdom of Dublin|King of Dublin]], died in 934 and Olaf succeeded him as king.<ref name="Hudson2004"/><ref name="Cannon479">[[#Cannon|Cannon (2009)]], p. 479</ref> The following year Olaf carried out a raid at Lagore crannog in [[County Meath]], and then looted the burial chamber at [[Knowth]] the following week.<ref name="D243244"/><ref name="Hudson2004"/>

Olaf is described as "Lord of the Foreigners" by the ''Annals of the Four Masters'' in 937,<ref>[[#A4M|Annals of the Four Masters]], s.a. 937</ref> at which time he went to [[Lough Ree]] and captured [[Amlaíb Cenncairech]], [[History of Limerick|King of Limerick]], and his troops after breaking their boats.<ref name="D243244"/><ref name="Hudson2004"/> This conflict can be ascribed to rivalry between the competing Viking settlements of Dublin and Limerick, with this event marking victory for Dublin. This period is considered to be the high-point of Viking influence in Ireland.<ref>[[#Downham|Downham (2007)]], pp. 41–42</ref> Having secured his position in Ireland, Olaf turned his attention to England and [[Northumbria]], which had once been ruled by Olaf's father and had been conquered in 927 by [[Æthelstan|Æthelstan of England]].<ref name="Cannon479"/> Olaf allied with [[Constantine II of Scotland]], whose kingdom had been invaded by Æthelstan in 934, and in 937, the same year as the victory over Limerick, Olaf and the Vikings of Dublin left for England.<ref name="D104106">[[#Downham|Downham (2007)]], p. 104–106</ref>

The allied forces of Olaf and Constantine met the forces of Æthelstan at the [[Battle of Brunanburh]], at a site which is the subject of much debate, although current scholarly consensus identifies the site as [[Bromborough]] in [[Cheshire]].<ref name="Hudson2004"/><ref>[[#Roffe|Roffe (2012)]], p. 120</ref> Olaf and Constantine commanded the Viking troops while Æthelstan alongside his brother [[Edmund I|Edmund]] led the English troops into the battle. Contemporary accounts indicate both sides suffered many casualties but the result was a decisive English victory. Olaf and Constantine survived the battle and returned to Ireland and Scotland respectively, but one of Constantine's sons died.<ref name="D104106"/> The battle is well-attested, with references in Irish chronicles, and a [[Battle of Brunanburh (poem)|poetic telling of the battle]] in the ''[[Anglo-Saxon Chronicle]]''.<ref>[[#A4M|Annals of the Four Masters]], s.a. 938</ref><ref>[[#ASC|Thorpe (1861)]], pp. 86–88</ref> The numerous references to it in various chronicles throughout the British Isles testify to its perceived importance at the time.<ref name="D104106"/>

The annals record Olaf's return to Ireland in 938 as well as a raid he carried out that year on [[Old Kilcullen|Kilcullen]] in modern-day [[County Kildare]], where he is said to have taken a thousand prisoners.<ref name="D243244"/> Æthelstan died in October 939 and very soon afterwards Olaf left for York where he was able to quickly establish himself as [[Scandinavian York|king of Northumbria]]. Olaf was joined in England by his cousin [[Amlaíb Cuarán|Olaf Cuaran]], and Olaf's brother [[Blácaire mac Gofrith|Blácaire]] was left to rule in Dublin while he was away.<ref name="FOP115">[[#ForteOram&Pedersen|Forte, Oram, and Pedersen (2005)]], p. 115</ref><ref name="D107110">[[#Downham|Downham (2007)]], pp. 107–110</ref> [[Symeon of Durham]]'s ''[[Historia Regum]]'' records that Olaf and the new English king Edmund met at Leicester in 939 and came to an agreement on dividing England between the two of them.<ref>[[#HB|Harper-Bill (1998)]], pp. 23–24, n. 155</ref> This peace was short-lived and within a few years of the agreement the Vikings had seized the [[Five Boroughs of the Danelaw|Five Boroughs]] of [[Derby]], [[Leicester]], [[Lincoln, England|Lincoln]], [[Nottingham]] and [[Stamford, Lincolnshire|Stamford]].{{#tag:ref|The exact dating of this invasion is uncertain. Symeon's ''Historia Regum'' records that it took place in 940 whereas the D-text of the ''Anglo-Saxon Chronicle'' says it occurred in 942–943, after Olaf's death.<ref name="D108110">[[#Downham|Downham (2007)]], pp. 108–110</ref>|group="nb"}}<ref name="D108110"/>
In 941 the ''[[Chronicle of Melrose]]'' records that Olaf raided an ancient [[Angles (tribe)|Anglian]] church at [[Tyninghame]] in what is now the [[East Lothian]] and at the time was a part of Northumbria.<ref>[[#CoM|Stevenson (1853)]], p. 97</ref><ref>[[#Stenton|Stenton (2001)]], p. 357</ref> This attack may have been more than just a raid, and may have been intended to secure a route through Scotland upon which communication between York and Dublin was reliant.<ref>[[#ForteOram&Pedersen|Forte, Oram, and Pedersen (2005)]], p. 111</ref> Olaf died in 941 and he was succeeded in Northumbria by Olaf Cuaran.<ref name="D107110"/> In recording his death, the annals title him "king of Danes" (''Chronicon Scotorum'') and "king of the [[Dubgaill and Finngaill|Fair Foreigners and the Dark Foreigners]]" (''Annals of Clonmacnoise'').<ref>[[#CS|Chronicon Scotorum]], s.a. 941</ref><ref name="Murphy152">[[#AClon|Murphy (1896)]], p. 152</ref>