Battlefield, Unknown, Co. Dublin

The placename Glen Máma has vanished from the landscape entirely. So too has Claen-Conghair, a stone significant enough to be mentioned in a poem recorded in the Annals of the Four Masters. What remains is a gap in the hills, roughly two kilometres long, running between Athgoe Hill and Busty Hill to the northwest and Windmillhill, a foothill of the Wicklow massif, to the southeast. According to the most current scholarly thinking, this is the most probable location of one of the more consequential battles of early medieval Ireland.

The engagement grew out of a political arrangement made two years earlier. In 997, a rígdál, or royal conference, was held at Clonfert, County Galway, between Brian Bóruma, king of Munster, and Máel Sechnaill, king of Meath and high king of Ireland. The meeting effectively divided the island between them, with Máel Sechnaill handing over hostages from Dublin and Leinster to Brian, making him their overlord in practice. This transfer of authority prompted Sitric mac Amlaíb, known as Silkenbeard, the Hiberno-Norse king of Dublin, to rebel. Brian marched north from Munster to reassert control. The Dubliners, likely accompanied by a Leinster contingent, moved to intercept him at a pass they believed they could hold. They could not. According to the Chronicon Scotorum and the Annals of Tigernach, the battle became a rout. Sitric's forces fled, pursued by Brian's army in what the Annals of Ulster described as a "great slaughter." The most notable casualty was Harald Olafsson, known in the annals as Aralt, son of Amlaíb, whose precise relationship to Sitric is uncertain but appears to have been close. The annalistic sources are not in full agreement about who fought on which side, partly because the various chroniclers wrote from different regional perspectives, each carrying their own political sympathies.

Tradition once placed the battle near Dunlavin in County Wicklow, and a proposal made in 1914 suggested the area around Ardclough on the Dublin-Kildare border. The current thinking, developed by the researcher MacShamráin and assessed by P. Walsh in 2017, points to the valley section of the Naas Road between Kill and Rathcoole as the most likely general area, given the requirement that the site fall within a day's march of Dublin. The coordinates provided are explicitly indicative rather than precise, and the exact location within the two-kilometre pass remains unidentified. There is no monument, no marker, and no formal access point to speak of. What a visitor can do is pull off the road somewhere near the valley and look at the hills on either side, Athgoe at 177 metres, Busty at 170, Windmillhill at 217, and consider that somewhere in this ordinary-looking corridor of county road and field, a winter battle decided the political shape of early eleventh-century Ireland.