ON THIS DAY: 1ST JANUARY 1577: Massacre at Mullaghmast

Rath of Mullaghmast. This is the ancient and historic Rath where the seven septs in Laois were lured and then slaughtered by English troops in 1577. Photo Credit: Belan Lodge

Clansmen and women of native Irish families were lured to discuss terms with the English at Mullaghmast, Co. Kildare. To the famous Rath at Mullaghmast which has figured in Irish history from as far back as 82AD. The site consists of a raised circular rampart breached at two sides allowing grazing cattle to wander through at will. It is now difficult to image that here was once the Palace of an Irish King frequently mentioned in the ancient Annals. It saw famous battles fought there in the 2nd and 3rd centuries; it was the ancient seat of the O’Toole clan who ruled over lands along the Kildare / Laois border.

The backdrop to this massacre was the plantation of ancient territories of Laois and Uí Failie, which had been sized from their native Irish occupants and given to English planters. Laois was renamed Queens County and Uí Failie (Offaly) was renamed Kings County. This was not taken lightly by the rightful owners and the two counties were in a state of perpetual war for over twenty years. Some of the English settlers, which included Sir Francis Cosby, decided to finally take out the native Irish families.  Known as an “enforcer”, Cosby was a law unto himself who terrorised and butchered the native Irish. If he wasn’t killing people he was swindling, blackmailing and double-crossing them.

Cosby had some 30 years previously petitioned the Queen to plant in Queens County (Laois) and ‘secured’ lands there at the natives expense. He would continue to ‘secure’ more and more lands. He was given the previous Franciscan religious house in Stradbally by Queen Elizabeth I in 1562, as a reward for his enthusiastic suppression of the natives. There were constant battles between Cosby and his English soldiers and the combined families of O’Mores and O’Connors. As the Gaelic Irish resistance to the Tudor conquest raged in Laois and Offaly, mainly through the above mentioned clans, Queen Elizabeth I ordered Sir Henry Sidney to stop at nothing to fulfil her orders to “cleanse” the region of “disordered persons”.

With the Queens troops and invaluable help of Lord Deputy Henry Sidney, they befriended and colluded with members of the O’Dempsey clan. They concocted a peace gathering where they would invite the clans and supposedly discuss peace terms with them.

Members of the Seven Septs of Laois – O’Moores, O’Kellys, O’Lalors, O’Dorans, O’Dowlings, Devoys, McEvoys, O’Nolans, O’Connors from Offaly – arrived at this place to what should have been a day of feasting and festivities at a banquet. Sidney entraped them in the Rath and suddenly they are surrounded by a hidden army of galloping horses thundering towards them. Chaos erupts. People are trampled and hacked to death by cavalry.  In a matter of no time, everyone is dead including the chiefs of the Seven Septs of Laois – O’Moore, O’Lalor, O’Kelly, O’Doran, O’Dowling, McEvoy and Devoy – and the chiefs of the O’Dunne, O’Molloy, O’Connor and O’More clans

They murdered up to 400 unarmed men, women and children; some were burned at the stake. 180 of the O’Moores alone were put to death. There have been attempts since the massacre to downplay the number of dead. But it was an English man, Captain Lee, who had originally suggested the peace meeting, who reported the number of 400 dead, and who distanced himself from Sidney; he was utterly appalled at what happened. He wrote a stinging condemnation to Queen Elizabeth.  Lee was later executed for supposedly offering support to the Irish during Hugh O’Neill’s rebellion. But in effect, his days were numbered once he exposed Cosby and Sidney.

A man from the Lalor family who had his suspicions about the meeting and had hung back, advanced cautiously after some time and at the entrance saw the dead bodies of his slaughtered kinsmen. It is said that he escaped back to Dysart on his  wounded horse which collapsed and died near Brackna Woods giving to the area a name which it still bears – The Bleeding Horse.

For the native Irish the savagery and brutality was a reminder that the planters were intent on conquering them by whatever means.

After the massacre, the English launched attacks on native strongholds including an attack on the O’Lalor’s castle in Dysart where it is believed that Captain Cosby ordered the hanging of O’Lalor’s wife on the postern gate along with her only child, which was hung from her long hair. They burned the Chieftains homes and villages, murdered their families and left orphaned children. Sidney returned to Dublin and assured the Queen that the two counties were now secure.

The following account of the massacre is found in the Annals of the Four Masters:[2]

  • 1577. A horrible and abominable act of treachery was committed by the English of Leinster and Meath upon that part of the people of Offaly and Leix that remained in confederacy with them, and under their protection. It was effected thus: they were all summoned to shew themselves, with the greatest number they could be able to bring with them, at the great ráth of Mullach-Maistean; and on their arrival at that place they were surrounded on every side by four lines of soldiers and cavalry, who proceeded to shoot and slaughter them without mercy, so that not a single individual escaped, by flight or force.

  •  In the year 1705, there was an old gentleman of the name of Cullen, in the County Kildare, who often discoursed with one Dwyer and one Dowling, actually living at Mullaghmast when this horrid murder was committed, which was about the sixteenth year [recté, nineteenth] of Queen Elizabeth’s reign; and the account he gives of it is, that those who were chiefly concerned in this horrid murder were the Deavils, the Grehams, the Cosbys, the Piggotts, the Bowens, the Hartpoles, the Hovendons, the Dempsys, and the FitzGeralds. The last five of these were, at that time, Roman Catholics, by whom the poor people murdered at Mullaghmast were chiefly invited there, in pretence that said people should enter into an alliance offensive and defensive with them. But their reception was to put them all to death, except one O’More, who was the only person that escaped. Notwithstanding what is said that one O’More only had escaped the massacre, yet the common tradition of the country is, that many more had escaped through the means of one Henry Lalor, who, remarking that none of those returned who had entered the fort before him, desired his companions to make off as fast as they could, in case they did not see him come back. Said Lalor, as he was entering the fort, saw the carcasses of his slaughtered companions; then drew his sword, and fought his way back to those that survived, along with whom he made his escape to Dysart, his family’s ancestral home.


Ruairí Óg Ó Mórdha, the Clan Chieftain, who was lucky enough not to attend the “Parley”, emerged as a strong uniting force and continued resistance against the native displacement from their lands in Laois. He was now the guerrilla chief of Laois and Offaly and while he lived, none of Cosby’s men were safe.

Attacks continued on the settlers with several towns burned to the ground. The events at Mullaghmast were so treacherous, that even English soldiers such as Captain Lee defected to the Irish cause. A rallying cry rang out across native territories; “Remember Mullaghmast”.

O’Dempsey, the Irish clan who colluded with the planters for silver, was hunted down and killed by one of Ruairí Óg Ó Mórdha’s chief lieutenants, Niall MacLaoiseach O’More.

Ouney, son of Ruairí Óg Ó Mórdha, slew Alexander and Francis Cosby, son and grandson of Cosby of Mullaghmast, and routed their troops with great slaughter at Stradbally Bridge, 19 May 1597.

For over four centuries the Cosby family has had a continuous tradition of military and civil service in the British imperial and colonial establishment.

The Cosby descendants still hold the same ground  – Electric picnic is held on it yearly.



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