Battle of Glenmalure

The Battle of Glenmalure (Cath Ghleann Molúra) took place in Ireland in 1580 during the Desmond Rebellions. An Irish Catholic force made up of the Gaelic clans from the Wicklow Mountains led by Fiach MacHugh O'Byrne and James Eustace, Viscount Baltinglas of the Pale, defeated an English army under Arthur Grey, 14th Baron Grey de Wilton, at the O'Byrnes' mountain stronghold of Glenmalure.

Background
Grey had recently landed in Ireland with reinforcements from England to put down the rebellion. His strategy was to meet O'Byrne's threat to the English heartland of Dublin and the Pale by attacking through the highlands to the south of the city. Against the advice of veteran commanders, he chose to lead his army (around 3,000 strong) through lowland Kildare and into the Wicklow Mountains, with the aim of taking the fastness at Balinacor in the Glenmalure Valley.

Battle
While trying to climb the steep slopes of the valley, the inexperienced English soldiers were ambushed by the Irish soldiers, who had hidden themselves in the woods. The English were sniped at for a long period of time before their discipline collapsed and they turned and fled down the valley. It was at this point that most of their casualties occurred, as the Irish soldiers left their cover and fell on the soldiers with swords, spears and axes. Hundreds of English soldiers, some of whom had thrown away their weapons in a panic, were cut down by the pursuing Irish soldiers as they tried to get away. The remaining English had to fight a rearguard action for several miles until they reached the town of Rathdrum.

Aftermath
Irish sources state that around 800 English soldiers were killed, though the English put their losses at 360 dead. Among those killed was Peter Carew, cousin of his namesake colonist who had made claims to, and won, large tracts of land in southern Ireland. The remainder of the English force retreated to lowland Wicklow and from there to Dublin. However, the following year, when offered terms, most of the Irish soldiers, including O'Byrne, came in and surrendered. The exception was Baltinglass, who fled for France.

The battle is commemorated in the folk song "Follow me up to Carlow".