[12] The Annals of Ulster reflect the viewpoint of areas of Ireland where they had influence, including Armagh, Fermanagh, Londonderry and the northern part of the province of Connacht.

[17] More recently, its worth as a historical record has been questioned; according to the 20th century medievalist Donnchadh Ó Corráin, it "influenced historiography, medieval and modern, out of all proportion to its true value".

[16] Although nineteenth century scholars, including John O’Donovan[18] and Todd,[19] and especially the Dunlavin-based clergyman John Francis Shearman (in 1830) were tempted to locate the battle-site in the vicinity of Dunlavin, Co Wicklow, within their lifetime the theory was disputed by Goddard Orpen,[20] and were disproved by Joseph Lloyd in 1914 and subsequently by Albha mac Gabhrain[21] who located the battle site beside Ardclough on the Dublin-Kildare border in 1914 (the Irish form of Dunlavin is in reality Dun Luadhain).

[9] Ailbhe Mac Shamhráin[7] wrote: Given the propensity for battles to take place in border regions,[23] it seems reasonable to seek a location close to the perimeter of the Hiberno-Norse kingdom of Dublin.

On that account, the suggestion of Lloyd,[24] which places the battle at a gap now crossed by the Naas Road on the section between Kill and Rathcoole, is still worthy of consideration.

[3] Late in 999, however, the Leinstermen, historically hostile to domination by either the Uí Néill overkings or the King of Munster, allied themselves with the Norse of Dublin and revolted against Brian.

[3] According to the 17th century Annals of the Four Masters, the following prophecy had predicted the Battle of Glenmama: They shall come to Gleann-Mama, It will not be water over hands, Persons shall drink a deadly draught Around the stone at Claen-Conghair.

The more partisan Cogad Gáedel re Gallaib indulges in hyperbole,[27] claiming that "since the Battle of Mag Rath to that time there had not taken place a greater slaughter".

[29] Tradition records that "the son of the King of the Danes", Harold Olafsson, was killed in the retreat, and was interred at the now obscure cemetery of Cryhelpe.

[3] Brian's forces marched quickly to Dublin (again confirming a Saggart-Ardclough location for the battle) reaching the town on New Year's Eve 999.

[3] Ailbhe Mac Shamhráin wrote: Allowance must be made here for poetic license but, event itself, some picture can be obtained of the wealth of the trading centre that was Dublin.

Ailbhe Mac Shamhráin[7] wrote: The implications here is that, from this time onwards, the Hiberno-Scandinavian ruler would hold his kingship from his Munster overlord.

Brian, at this stage, aspired to an even tighter dominance of Dublin than that secured by his rival, Máel Sechnaill mac Domnaill, ten years earlier.

With renewed confidence, he again moved against Máel Sechnaill mac Domnaill, even if his initiatives of 1000–1001 resulted in setbacks, one expedition into Brega resulted in his advance cavalry being slaughtered by the Uí Néill, another foray was reversed in Míde (Co Westmeath), and the Dál Cais river-fleet was impeded by the King of Tara and his Connachta allies having constructed a barrier across the Shannon.

[31][38] Máel Sechnaill, who found the support of the northern kings slipping away,[39] felt obliged to submit and a new political order was created.

Ailbhe Mac Shamhráin[7] wrote: Glenn Máma gave Brian a psychological advantage over the king of Tara and increased his readiness to break the Agreement of Clonfert.

Through achieving effective dominance of Dublin, Brian acquired a military (aside from a psychological) advantage over Máel Sechnaill, which helped him in his endeavours to reach beyond the lordship of Leth Moga.