She was the eldest daughter of David Roche, 7th Viscount Fermoy and widow of Donal MacCarthy Reagh of Kilbrittain,[58][59][60] who had died in 1636.

Under Strafford's guidance, the parliament unanimously voted four subsidies of £45,000[122] (equivalent to about £10,100,000 in 2023[109]) to raise an Irish army of 9,000[123] for use against the Scots in the Second Bishops' War.

[144][145] Seeing the King weak[146] and trying to oppose plantations,[147] Sir Phelim O'Neill launched the Rebellion from the northern province of Ulster in October 1641.

[150] In Munster Muskerry socialised with Richard Boyle, 1st Earl of Cork, an English Protestant established in Ireland, with whom he had opposed Strafford.

[163][164] Muskerry believed Phelim O'Neill acted under a royal warrant,[165] but the King had already denounced the Irish insurgents as traitors in January.

[172] He was also prompted to take up arms by the atrocities committed by William St Leger against the Catholic population[173][174] and by the approach of Richard Butler, 3rd Viscount Mountgarret with his rebel army.

[186] On 13 April Murrough O'Brien, 6th Baron Inchiquin, an Irish Protestant,[88] lifted the siege by driving the insurgents from their base at Rochfordstown.

[206] In July, Muskerry and Patrick Purcell used artillery, captured at King John's Castle, to take Kilfinny, defended by Elizabeth Dowdall,[207] Waller's mother-in-law.

[239] Muskerry was about to take Cappoquin but engaged in parleys[240] and was outwitted by Inchiquin, who delayed the town's surrender until September when the cease-fire ended the war.

[251] In November 1643 the Supreme Council appointed seven delegates,[252] with Muskerry as leader,[253] to submit grievances to the King[254] and negotiate a peace treaty.

[264] Owen Roe O'Neill led the Confederate Ulster army, deployed on that front, but the Supreme Council imposed Castlehaven as general-in-chief for the campaign of 1644.

[289][290] Sir Charles Coote divulged it in October after he found a copy in the luggage of Malachy Queally, bishop of Tuam, killed in action near Sligo.

[294] On his way to Kilkenny, the Confederate capital, Rinuccini visited Macroom Castle where Lady Muskerry and her 11-year-old eldest son, Charles, received him while her husband was negotiating with Ormond in Dublin.

The Munster Army, under Glamorgan, favoured by Rinuccini, was sent to besiege Bunratty Castle near Limerick,[315] into which the 6th Earl of Thomond, a Protestant, had admitted a Parliamentarian garrison in March 1646.

[318] After a setback on 1 April, in which the garrison drove the besiegers from their camp at Sixmilebridge,[319] the Supreme Council replaced Glamorgan with Muskerry at the end of May.

[325] On 13 June arrived the news of Owen Roe O'Neill's victory over the Covenanters at Benburb,[326][327] won with the financial support from the nuncio.

[348][349] On 18 September, Rinuccini overturned the Confederate government in a coup d'état[350] with help of the Ulster Army, which Owen Roe O'Neill had marched to Leinster.

[351] On 26 September[352] Rinuccini made himself president and appointed a new, the seventh, Supreme Council[353][354] in which sat Glamorgan, Fermoy, and Owen Roe O'Neill.

[360][361][362] Having failed to take Dublin, Rinuccini released Muskerry and other political prisoners as demanded by Nicholas Plunkett,[363] and called a general assembly, which met on 10 January 1647 in Kilkenny.

[379] On 12 June Muskerry, together with Patrick Purcell, rode over from the council meeting to the army's camp[380] where the troops acclaimed him as their leader and turned Worcester out of his command.

[392] Towards the end of 1647, the Supreme Council sent Muskerry, Geoffrey Browne, and the Marquess of Antrim to negotiate with the exiled Queen Henrietta Maria, at the Château-Neuf de Saint-Germain-en-Laye, France.

They wanted to invite the Prince of Wales, the future Charles II, then aged 17, to Ireland,[393] and negotiate another peace to replace the one concluded with Ormond.

[399] However, 1648 was the year of the Second English Civil War[400] and plans were made for the Prince of Wales to go to Scotland to support the Engagers rather than to go to Ireland, but eventually, he stayed in France.

[415] He wanted to avenge the uprising of 1641, confiscate enough Irish Catholic-owned land to pay off the English Parliament's debts, and eliminate a dangerous outpost of royalism.

[433] Muskerry fell back into the mountains of Kerry and based himself at Ross Castle near Killarney,[434] owned by Sir Valentine Browne, his nephew by his sister Mary.

He returned to Ireland late in 1653[454] landing at Cork[455] to recruit soldiers for service on the continent[456] but was arrested for war crimes[457] and detained[458] until the opening of his trial on 1 December in Dublin.

[467] Lady Ormond, who had been allowed to return to Ireland from her French exile,[468] secretly visited Gerard Lowther, president of the High Court of Justice at the time,[469][470] who gave her legal advice for Muskerry.

Henrietta Maria, now the Queen Mother, still lived there, but in July 1654 Charles II and his exile court were about to leave France and start their wanderings in the Netherlands and Germany.

In November 1654 she wrote to Queen Marie Louise Gonzaga of Poland proposing to employ Muskerry and his followers – 5,000 men – in Polish service.

[529] The Catholic political pamphlet The Unkinde Deserter of Loyall Men and True Frinds claims that in his last hour Clancarty expressed regret at having trusted Ormond.