Murrough O'Brien, 1st Earl of Inchiquin, 1614-74
Irish Protestant leader who changed allegiance twice during the Confederate Wars and became notorious as "Murrough the Burner"; he later converted to Catholicism
Murrough O'Brien was the eldest son of Dermond O'Brien, fifth Baron Inchiquin, and his wife Ellen, daughter of Sir Edmond Fitzgerald of Cloyne. His father's family claimed descent from the earliest kings of Ireland while his mother was the daughter of a powerful Anglo-Norman ("Old English") dynasty.
Murrough succeeded as the sixth Baron Inchiquin at the age of ten upon the death of his father in 1624. His estates were held in wardship by Sir William St Leger, President of Munster, a Protestant nobleman who sought to increase his power in Ireland by arranging the marriage of his daughter Elizabeth (d.1685) to Inchiquin in October 1635. Inchiquin remained under St Leger's influence even after he gained control of his estates in 1636. After serving in the Spanish Army of Italy during 1638-40, Inchiquin returned to Ireland and was appointed vice-president of Munster in April 1640.
The Confederate War
During the Irish Uprising of 1641, St Leger took command of government forces in Munster in an uneasy alliance with Richard Boyle, the powerful Earl of Cork. Inchiquin quickly rose to prominence owing to his military experience in the Spanish army, though as a native Irishman, he was regarded with suspicion by Lord Cork. After St Leger's death in April 1642, Inchiquin and Cork vied for control of the Munster Protestants. Inchiquin defeated Viscount Muskerry and the Catholic insurgents at the battle of Liscarrol in August 1642 and ruthlessly kept control of south-western Ireland until the Cessation of Arms was signed between the Confederates and the King's representative the Marquis of Ormond in September 1643.
During the Cessation, Inchiquin sent five Irish regiments to reinforce the King's army in England in the expectation that he would be granted the presidency of Munster, which had remained vacant since St Leger's death. In February 1644, Inchiquin went to Oxford expecting to be granted the King’s commission but Charles snubbed him by giving the presidency to the Earl of Portland. Enraged, Inchiquin returned to Ireland and declared for Parliament in July 1644. After he had expelled the Catholics from Cork, Youghal, and Kinsale, the English Parliament appointed him president of Munster, which he governed without reference to the King's representatives Portland and Ormond. However, Parliament was unable to spare him many supplies so Inchiquin remained on the defensive against the Confederates.
Although he managed to maintain his garrisons in Munster, Inchiquin's position was complicated by factional rivalry with Lord Broghill, son of the Earl of Cork. Their enmity intensified over Broghill's insistence that Irish soldiers should subscribe to the Solemn League and Covenant, which Inchiquin refused to sign, and over Parliament's appointment of Viscount Lisle as lord-lieutenant of Ireland in April 1646, who tended to defer to Broghill and oppose Inchiquin. After Lisle's abrupt departure from Ireland in April 1647, Broghill continued to undermine Inchiquin's position with accusations of disloyalty at Westminster.
Murrough the Burner
Inchiquin decided to assert his authority in Munster by mounting a major military offensive against the Confederates during the summer and autumn of 1647. He stormed and captured Dungarvin, Cappoquin and other garrisons, gaining a terrible reputation amongst the Irish as Murchadh na d'Tóiteán, "Murrough the Burner", after his troops stormed the Rock of Cashel, where they burned down the defences, massacred soldiers, civilians and priests and desecrated the Cathedral of St Patrick. Desperate to prevent Inchiquin from joining forces with Colonel Jones' Parliamentarian troops at Dublin, the Confederates sent Viscount Taaffe into County Cork with six thousand foot and twelve hundred horse. Although heavily outnumbered, Inchiquin inflicted a decisive defeat on Taaffe at the battle of Knocknanuss in November 1647, which left him master of southern Ireland.

Despite Inchiquin's military success, he received little support from London, where Ireland was not regarded as a priority so long as Dublin was secure. His marginalisation by the Parliamentarians and his increasing alarm at the dominance of the radical Independents at Westminster prompted Inchiquin to change sides once again. He declared for the King in April 1648 and negotiated for a new alliance with the Confederates. The resulting Inchiquin Truce of May 1648 was fiercely opposed by the Pope's representative Archbishop Rinuccini and led to civil war within the Confederacy between Rinuccini's supporters and the Anglo-Irish lords on the Supreme Council. However, Inchiquin finally received his coveted royal commission as Lord-President of Munster in July and welcomed the Marquis of Ormond when he returned to Ireland in September 1648 to negotiate an alliance between the Royalists and the Confederates.
In March 1649, Inchiquin joined forces with the Confederate lords Taaffe and Castlehaven to drive the renegade Owen Roe O'Neill out of Leinster. During the summer, he captured the garrisons at Trim, Drogheda and Dundalk. In July, Ormond sent Inchiquin back to Munster with three cavalry regiments in order to guard against the possibility of Cromwell's army from England landing there, but in Inchiquin's absence, Ormond was defeated by Colonel Jones at the battle of Rathmines near Dublin in August 1649. After this defeat, large numbers of Protestants in Inchiquin's army defected to Parliament. Inchiquin struggled to resist the relentless advance of Cromwell's invasion but, one-by-one, the Munster garrisons capitulated. In March 1650, Inchiquin was defeated by his old enemy Lord Broghill at Mallow in County Cork. Mistrusted by the Catholic Confederates, Inchiquin left Ireland for exile in France in December 1650.
Exile & Restoration
Thanks to the influence of the Marquis of Ormond, Inchiquin found favour with the exiled Charles II, who granted him the earldom of Inchiquin in 1654. He served on Charles' council and governed the disputed territory of Catalonia for France against Spain during 1654-8. After a period of acute illness in 1657, Inchiquin unexpectedly converted to Catholicism. His sudden conversion caused an irreconcilable split with his devoutly Protestant wife Elizabeth and alienated him from Ormond and his friends at court.
In 1659, Inchiquin was offered a commission in the Portuguese army but was captured by Algerian corsairs on his way to take up his command in company with his eldest son William. They remained prisoners until the newly-restored Charles II intervened on their behalf in the summer of 1660. During his imprisonment, Inchiquin wrote letters to priests in which he sought atonement for his past sins in persecuting the Catholic church.
After his release, Inchiquin found favour with the Queen Mother Henrietta Maria and was appointed steward of her household. Through Henrietta's influence, Inchiquin recovered his estates in Munster but, because of his religion, he was denied the presidency which was granted to his old enemy Broghill, now Earl of Orrery. However, Inchiquin became reconciled with Orrery, and his heir William O'Brien married Orrery's daughter Margaret Boyle in 1665. After commanding an unsuccessful expeditionary force sent by Charles II to help the Portuguese in 1662, Inchiquin lived quietly in Ireland until his death in 1674. He was succeeded as second Earl of Inchiquin by his eldest son, William, governor of Tangier.
Richard Bagwell, Murrough O'Brien, 1st Earl of Inchiquin, DNB 1894
Patrick Little, Murrough O'Brien, 1st Earl of Inchiquin, Oxford DNB, 2004