In 972, The King of Leinster based at Lyons Hill, Dómnall Claen mac Lorcáin was responsible for the slaying of his relative form the dynasty based at Naas, Murchad mac Finn, in what the Annals of Ulster described as “treacherous circumstances.
Murchad’s children were to feature prominently in events over the coming decades: Mael Mórda became King of Leinster and Gormflaith/ Kormloð was to marry two (and possibly three) of the most powerful kings of the era.
The “treacherous killing” of Murchad started a feud between the Ui Dunnchada (Ardclough) and Ui Faelán (Naas) dynasties of Leinster kings that was to lead to two important battles (or perhaps restarted the feud, because Muiredach mac Faeláin in 967, Dómnall Claen’s uncle had been killed in 967 by Gormlaith’s first husband Amlaíb/Olaf Cuarán, the Viking king of Dublin rememebred as Havelock the Dane in Middle English romance).
In 979 Dómnall Claen was taken prisoner by the Danes of Dublin and was freed only after the intervention of former High King Máel Sechnail, who invaded Dublin in 981 after its capture by the Waterford Vikings and explusion of Amlaib. Dómnall Claen went to battle against the Dublin Vikings again in 983 but was defeated by an alliance of High King Máel Sechnaill and Amlaíb’s son and Sitriuc’s half brother Glún-Iarainn/Járnkné, after which Máel Sechnaill ravaged Kildare and Glún-Iarainn burned Glendalough.
After Dómnall Claen was killed by the Uí Chennselaig in 984 his son Donchada assumed the kingship and began a nine year rivalry with his Uí Fáeláin rival, Máel Mórda mac Murchada and his nephew, Sitriuc Silkbeard, king of the Vikings of Dublin.
This rivalry was responsible for provoking a war between Máel Sechnaill mac Dómnaill (948–1022), and Brian Bóruma (c.941–1014) for supremacy and the High Kingship.
It began in earnest in 999 when Donchada mac Dómnaill Claen was captured by Máel Mórda and his nephew Sigtrygg (Sitric Silkbeard, the son of Olaf Cuaran). This was a challenge to Máel Sechnaill, as the province’s overlord, and he responded by ravaging Leinster.
Brian Bóruma saw this as an opportunity to intrude into Leinster’s affairs, and late in the year he led an army there which defeated the combined forces of Leinster and Dublin at the battle of Glenn Máma, on a site to the east of Oughterard Hill adjoining Lyons.
The battle appears as an entry in a number of the Irish annals: namely, Annals of the Four Masters, the Annals of Ulster, the Chronicon Scotorum and the Annals of Innisfallen. The Irish annals “constitute a substantial and unique collection of annual records of ecclesiastical and political events”, as written in the Irish monasteries from the mid-6th century to the end of the 16th century. Although the historical status of the retrospective entries on the pre-Christian and early Christian periods are uncertain, entries from the later 6th century on are contemporaneous Collation of the annals has provided a reliable chronology for events in medieval Ireland. There was cross-over between many of the annals, parts of which were copied from each other, but each collection reflects something of the monastery and district in which it was compiled.
The Annals of Ulster reflect the viewpoint of the northern Ui Neill, modern counties Armagh, Derry, Fermanagh, and the northern part of the province of Connacht. It was authored by Cathal Mac Manus, a 15th century diocesan priest, and is considered one of the most important, “possibly the single most important”, record of events in medieval Ireland. The Chronicon Scotorum (as with the Annals of Tigernach, Clonmacnoise and Roscrea) reflects political and ecclesiastical events relevant to the monastery and environs of Clonmacnoise in Leinster. The Annals of Innisfallen reflect the Munster viewpoint, in particular the monastery of Emly.
In the 1630s, the texts of these annals were compiled into a single, enormous compendium, known as the Annals of the Four Masters. In the process, the authors sometimes modified the chronology and content of some of the materials, and is thus chronologically untrustworthy. However, it is recognised that they saved for posterity material that would otherwise have been lost, and the entry contains the longest annalistic account of the battle.
The principle source of information about the battle is the much more detailed 12th century Cogadh Gaedhel re Gallaibh, edited by James Henthorn Todd (1867), and includes a bardic poem commemorating the battle. “Part compilation and part romance”, it was written based on the extant annals as a propaganda work to glorify Brian Ború and the Dál Cais dynasty. 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”. However, historians still recognise it as the “most important of the Irish sagas and historical romances concerning the Vikings”.
Todd includes in his translations of the Cogadh Gaedhel re Gallaibh a lengthy claim for the location of the battle site by John Francis Shearman, the former Roman Catholic curate of the neighbourhood of Dunlavin, Co Wicklow. This theory is no longer accepted and the battle was identified as a site beside Cnoc Liamhna by Joseph Lloyd in 1914 in an article in the Journal of the Kildare Archaeological Society Vol VII, No 6 (July 1914), The identification of the battlefield of Glenn Máma and confirmed in 2001 by Ailbhe MacShamhráin (1954-2011) in Medieval Dublin, edited by Sean Duffy, 2001.
In 997, at a royal meeting at Terryglass, Brian Boru, King of Munster, met with his long-time rival Máel Sechnaill mac Domnaill, who was at the time High King of Ireland. Although the idea of the high-kingship is considered mainly an anachronistic invention, it came into vogue in the 10th century to denote a king who had enforced his power over external territories. Máel Sechnaill assumed the Irish high-kingship after the Battle of Tara in 980.
The two kings made a truce, by which Brian was granted rule over the southern half of Ireland, while Máel Sechnaill retained the northern half and high kingship. In honour of this arrangement, Máel Sechnaill handed over to Brian the hostages he had taken from Dublin and Leinster; and in 998, Brian handed over to Máel Sechnaill the hostages of Connacht.
In the same year, Brian and Máel Sechnaill began co-operating against the Norse of Dublin for the first time. 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.
According to the 17th century Annals of the Four Masters, the following prophecy had predicted the Battle of Glenn Máma:
- They shall come to Gleann Máma,
- It will not be water over hands,
- Persons shall drink a deadly draught
- Around the stone (Imon Cloich) at Claen-Conghair.
- From the victorious overthrow they shall retreat,
- Till they reach past the wood northwards,
- And Ath-cliath the fair shall be burned,
- After the ravaging the Leinster plain.
The Battle of Glenn Máma was fought in the valley behind Oughterard hill. Imon Cloich may even be an early reference to Ardclough. The Annals of the Four Masters records that Brian and Máel Sechnaill united their forces and according to the Annals of Ulster, they met the Leinster-Dublin army at Glenn Máma on Thursday, 30 December, 999, at Uí Donnchada beside Lyons, the ancient stronghold of the Uí Donnchada sept of the Uí Dunlainge Kings of Leinster. On the Leinster/Viking side Máel Mórda of Leinster and Sigtrygg of Dublin were accompanied into the battle by Cuilen Eitigensson and Arald msc Amhlaibh, Harold Olafsson, who was to die in the battle.
John Francis Shearman theorised that Brian had anticipated their movements, and cut off their retreat “in the narrow defile” of Glenn Máma, with the Hill of Lyons and Athgoe Hill on one side and Castlewarden Hill, Rusty Hill and Windmill Hill on the other. With no room for a regular encounter, the flight of the Danish army may have begun immediately. The main body of the army rallied north east of the battlefield towards Esker (Liscaillah), where thousands were said to have fallen. The remnant of the defeated army fled about a mile east of the ford, and were utterly routed.
A smaller body of cavalry fled northwards, possibly to reach the ford of the Liffey at Castledillon, and some of them perished crossing at Oughterard. A third party fled from the valley eastward. Brian pursued them, and his son Murchad allegedly pulled Máel Mórda from the yew tree in which he was hiding (at Parkaree, Páirc a Ríogh, “the King’s field”?). According to the propagandist Cogadh Gaedhel, the battle was “bloody, furious, red, valiant, heroic, manly; rough, cruel and heartless.” It stated that there had been no greater slaughter since the 7th century Battle of Mágh Rath.
Later historians have also depicted the victory of the The Munster-Meath army over the Leinster-Dublin army as decisive. Ó Corráin refers to it as a “crushing defeat” of Leinster and Dublin, while The Dictionary of English History says the battle effectively “quelled” the “desperate revolt” of Leinster and Dublin. Tradition records that “the son of the King of the Danes”, Harold Olafsson, was killed in the retreat, and was interred at Clownings.
Brian took Máel Mórda of Leinster prisoner and held him until he received hostages from the Leinstermen. It was alleged that 7000 Norse fell in the battle. This was at a time when warfare was fought on a very limited scale, and raiding armies generally had between a hundred and two hundred men. Most importantly, the defeat left the road to Dublin “free and unimpeded for the victorious legions of Brian and Maelsechlainn”.
The victory was followed up with an attack on the city of Dublin. The 12th century Cogadh Gaedhil re Gallaibh gives two accounts of the occupation: that Brian remained in Dublin from Christmas Day until Epiphany (January 6th), or from Christmas Day until St Brigid’s Day (February 1st). The later Annals of Ulster gives a date of December 30th for the Battle of Glenn Máma while Annals of Inisfallen dates Brian’s capture of the city two days later, to 1 January 1000. According the much more reliable Annals of the Four Masters and the Chronicon Scotorum, Dublin was only occupied for a week by Munster forces.
According to the Cogadh Gaedhil re Gallaibh, Sigtrygg’s flight from the city brought him north, first to the Ulaid and then to Áed of Cenél nEógain. Since Sigtrygg could find no refuge in Ireland, he eventually returned, submitted to Brian, gave hostages and was restored to Dublin. This was three months after Brian ended his occupation in February. In the meantime, Sigtrygg may have temporarily “turned pirate” and been responsible for a raid on St David’s in Wales. Brian gave his own daughter by his first wife in marriage to Sigtrygg. Brian in turn took as his second wife Sigtrygg’s mother, the now thrice-married Gormflaith. The cessation of revolt was followed by over a decade of peace in Dublin while Sigtrygg’s men served in the armies of Brian. However, Sigtrygg never forgot the insult of the Ulaid, and in 1002 he had his revenge when his soldiers served in Brian’s campaign against the Ulaid and ravaged their lands.
Glenn Máma is noted as one of the few occasions when Brian engaged in open battle. Brian captured Dublin on New Year’s Day 1000 and at Athlone in 1002 took the hostages of Connacht and Meath thus ending Máel Sechnaill’s first possession of the high-kingship.
When Brian Bóruma campaigned again in Leinster in 1003, he deposed the Ardclough/Lyons king Donchada mac Dómnaill Claen and surprisingly set up in his stead on the Uí Fáeláin rival (and Glenn Máma opponent), Máel Mórda mac Murchada. Ardclough/Lyons was never to serve as the centre of the Leinster kingship again. Both Máel Morda and Sitriuc rebelled again and were to become Brian’s foes and opponents at the Battle of Clontarf (1014). While Máel Morda was slain, Sitriuc survived to rebuild Dublin’s economy.
After Clontarf, the Kingship of the Uí Dúnlainge was held by the Uí Muiredaig and shortly afterwards the Kingship of Leinster reverted from the Uí Dúnlainge to the Uí Chennselaig dynasty based in Ferns, County Wexford.