Brian Boru's decisive victory at Glenn Máma in 999 forced Dublin's submission and set the stage for the later Battle of Clontarf in 1014.
Key Facts
- Date
- AD 999
- Location
- Near Lyons Hill, Ardclough, County Kildare
- Conflict
- Leinster revolt of 999–1000 against Brian Boru
- Outcome
- Crushing defeat of Leinster and Dublin forces
- Consequence
- Occupation of Dublin by Munster forces
- Follow-on event
- Battle of Clontarf, 1014
By the Numbers
Location
Cause → Event → Consequence
The kingdoms of Leinster and Dublin revolted against the authority of Brian Boru, King of Munster, in 999. King Máel Mórda of Leinster led the allied Leinster and Dublin armies in opposition to Brian, who had been extending his power over the other Irish kingdoms.
The combined forces of Munster and Meath, commanded by Brian Boru and High King Máel Sechnaill II, met the Leinster-Dublin alliance in a narrow valley near Lyons Hill. The confined terrain caused a rout of Máel Mórda's army, and the fleeing forces were pursued and slaughtered at fording points along the River Liffey.
Brian Boru's forces occupied Dublin, and both Máel Mórda of Leinster and King Sigtrygg Silkbeard of Dublin submitted to him. The settlement proved temporary; Leinster revolted again, ultimately leading to the Battle of Clontarf in 1014, which became one of the most consequential engagements in medieval Irish history.
Belligerents & Mobilization Analysis
Side A
2 belligerents
Brian Boru, Máel Sechnaill II.
Side B
2 belligerents
Máel Mórda of Leinster, Sigtrygg Silkbeard.