Today in History: Death of Sir Francis Cosby in the battle of Glenmalure

Illustration of the Battle of Glenmalure. Artist unknown. Image found at Pinterest where it was saved from

Glenmalure is a defile deep in the Wicklow mountains in the south east of Ireland. In 1580 it was at the centre of the territory occupied by the O’Byrne clan. Feagh MacHugh O’Byrne, a man in his mid-forties, had recently been chosen as the clan chief. Like other Irish clans they operated a policy of harassing the English, making brief incursions towards the Pale. Taking advantage of a rebellion in the south west of the island he had brought together a number of other clans with the aim of forcing the English settlers out of Ireland.

It was not only the clans that were contemplating rebellion. Disgruntled by the preference given to settlers such as Francis Cosby by the authorities in Dublin, old Anglo-Irish Catholic families, descended from the original Norman colonists, felt left out. The young James Eustace, 3rd Viscount Baltinglas, was one of these. Like many others he had been educated in Catholic institutions in Europe and spent some time in Rome. These disgruntled traditionalists found moral support among continental Catholics, especially in Spain. They were buoyed by the prospect of a Spanish invasion.

It was barely a year since James’s father was killed by Feagh’s father. That did not prevent him joining forces with O’Byrne and other Leinster clans, among them the Kavanaghs and the MacMuroughs.

The O’Moores had been routed by a group led by Francis Cosby two and half years before. He had employed a long established ruse: invite your enemy to talk peace then ambush and massacre them. One of the Marcher Lords that came to Ireland four centuries before had employed the same tactic at Abergavenny. The place Francis chose was a wooded hill in the west of county Kildare, called Mullaghmast. One of the few surviving O’Moors, Francis’s sworn enemy Rory Oge, Feagh’s brother-in-law, had later been murdered by a cousin. Rory’s wife, Feagh’s sister, had been murdered in 1577 during a raid on Rory’s camp by English settlers. It is not known if Francis was responsible for this raid but it seems more than likely.

O’Byrne, emboldened by the apparent breadth of opposition to the English, had extended his field of operation, setting fire to properties in the north of County Carlow, close enough to the territory that Francis by now regarded as his own to be a source of concern. When a newly appointed Lord Deputy arrived with reinforcements and a determination to put down the rebellions, Francis must have been pleased.

Strategy opposed

The man in question was Arthur Grey, 14th Baron Grey de Wilton. Naas, in County Kildare, was his chosen rendezvous point. He had with him about 1500 English troops, most of them raw recruits. They were joined by a similar number of men assembled from the various planter kerns, including one led by Francis.

When Grey explained his strategy some of those kern captains expressed their opposition to the plan. Grey was new to Ireland. True, he was a seasoned fighter, having served in northern France where the English had finally ceded control to the French. Perhaps that defeat still rankled; so, perhaps, did his father’s humiliation at Leith 20 years earlier. Perhaps here in Ireland there was an opportunity to demonstrate the superiority of English fighting men.

The planters, for their part, had forty and more years of experience dealing with the clans. They understood only too well the guerrilla tactics favoured by the O’Moores, O’Connors, O’Tooles and O’Byrnes. They also knew the terrain Grey had chosen as his battlefield. The forested hills that enclosed the glen would make a perfect hiding place for Irish fighters. Despite the superiority of numbers and weaponry held by the English, the clansmen surely held the territorial advantage.

Grey ignored the warnings. Half of his force, mostly mounted cavalry, were held back at the entrance to the glen. Sir George Moore led the attacking force, accompanied by Francis and the other kern captains. The intention seems to have been to flush out the rebels who would be trapped between Sir George’s group and Grey’s party.

Sir William Stanley, one of the officers in charge of the descent in to the glen describes it thus: “When we entered the foresaid Glen, we were forced to slide some tymes three or four fadoms er we colde staie our feete; it was in depth where we entered, at the least a myie, full of stones, rocks, bogs and wood, in the bottom thereof a ryver full of lose stones, wch we were dryven to crosse dyverse tymes“.

Another account uses similar words: “Under foot it is boggie and soft, and full of great stones and slipperie rocks, verie hard and evill to pass through; the sides are full of great and mightie trees upon the hits and full of bushments and underwoods“.


The English quickly came under fire from the hill on the north side of the glen. By now they were close to exhaustion from their exertions descending the mountainside. Nevertheless, George Moore ordered them to climb the almost sheer slope to the north in order to destroy their attackers, unaware that there were many more just waiting for such a move. These now descended upon the English.

One can only begin to imagine the horror that ensued. I can’t help recalling Tennyson’s description of the rout of “the six hundred” cavalrymen in the Crimea almost 300 years later. On this occasion there were 1500, mostly on foot. Half of them died, including Francis.

The poet Edmund Spenser, who was also present in his capacity as Grey’s secretary, described how most were so exhausted they were unable to run fast enough to escape the swords and battle axes of their pursuers. Another witness tells of the young Sir Peter Carew, who had participated in full armour, pausing to rest before being set upon by a party of rebels. If comparatively young men were so afflicted, how would conditions have assailed the septuagenarian Francis? As a captain of the kern, would he have been mounted? Carew, it seems, was not. No doubt the terrain was unsuitable for mounted combat.

Among the force that Francis commanded were some whose loyalty was questionable. This was surely one of the reasons he had counselled against the strategy in the first place. Now they changed sides. It is even possible that it was a shot fired by one of these that killed him.

Last moments

There is no way of knowing whether his death was instantaneous. If it was prolonged, as a fatal wound slowly bled out, what were his thoughts in those last moments? Did he have any regrets about coming to Ireland and making his home here? Did he continue with his belief that here was somewhere his descendants could thrive and prosper? Was his last emotion one of anger that Grey’s foolishness had ended in the way he, Francis, and others had predicted? That the settler’s dreams were, perhaps, ended here, in this dark vale stained with the blood of friends and allies?

He would have been wrong if that was his last thought. The English defeat at Glenmalure was the bloodiest since the confrontations between Richard II and Art MacMurragh in 1399. But it was far from being the end of English domination of its island neighbour. And Francis’s descendants still occupy land in the valley Francis chose as his home almost five centuries ago.

According Emmet O’Byrne, in an article published in a 1998 edition of the Journal of the Rathdrum Historical Society and reproduced on the Eustace family website: “Tradition suggests Feagh kept Cosby’s body as a prize of war. It may have been buried secretly in this remote place on his command.”

4 thoughts on “Today in History: Death of Sir Francis Cosby in the battle of Glenmalure

  1. Hi Frank. I’m leaving this comment via the WP app, just to let you know that there’s a problem with this post. I’ve tried it in Safari, Edge, and the app’s Reader and just get error messages. One of them said it was something to do with Cloudfare, if that helps. You may like to investigate further!

    Liked by 1 person

    1. Thanks Clive. I was/am still aware of the problem. I am told it will be sorted in the next day or two. It is annoying because I missed the opportunity to share the link on the relevant date. Quite a few people have been able to access the post, as you did. I assume via the WP reader. Hope all is well with you, Frank

      On Wed, Aug 25, 2021 at 11:10 AM Frank Parker's author site wrote:


      Liked by 1 person

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