Callaghan was born in the late 1630s or the early 1640s, probably at Blarney Castle, County Cork, Ireland. He was the second son of Donough MacCarty and his wife Eleanor Butler. His father was from the MacCarthy of Muskerry dynasty, an ancient Gaelic Irish family descended from the kings of Desmond. At the time of his birth, Callaghan's father was the 2nd Viscount Muskerry, but he would later become Earl of Clancarty. Callaghan's mother was the eldest sister of James Butler, 1st Duke of Ormond. She was from the Butlers, an Old English family that had played an important role in south-eastern Ireland since the Norman invasion. Callaghan's parents were both Catholic; they had married before 1641. Callaghan appears below among his brothers as the second son:
Charles, predeceased his father, being slain in the Battle of Lowestoft, a naval engagement;
Callaghan ; and
Justin, fought for the Jacobites and became Viscount Mountcashel.
MacCarty's father was allowed to embark to Spain. The family's estates were lost in the Act of Settlement of 1652, passed by the English Rump Parliament on 12 August. Young Callaghan, aged about five, his mother, and his siblings, except his eldest brother, Charles, had fled already to France some time before the fall of Ross Castle, his father's last stronghold. His mother lived with her sister Mary, Lady Hamilton, in the convent of the Feuillantines in Paris. On 27 November 1658 his father was created Earl of Clancarty by Charles II in Brussels, where the King was then in exile. By this advancement the title of Viscount of Muskerry became a subsidiary title of the family, which was given as a courtesy title to the Earl's heir apparent. Thus Callaghan's elder brother Charles was from there on styled Viscount Muskerry. A title he would keep until his death; he never succeeded his father to the earldom.
At the Restoration his parents and his brother Charles returned to the British Isles with his family. His father, Earl Clancarty, recovered his estates in the Act of Settlement 1662. His brother lived at the court at Whitehall. It seems that Callaghan, aged about 13, stayed behind in France where he was a monk in a monastery.
Earl of Clancarty
On 4 March 1665, the Second Anglo-Dutch War broke out. Three months into the war, on 3 June 1665 O.S., his brother Charles, Lord Muskerry, was killed on the flagship, the Royal Charles, in the Battle of Lowestoft, the first major naval engagement of the war and an English victory. His brother had an infant son, also named Charles, who succeeded him as heir apparent and Viscount of Muskerry. However, their father, the 1st Earl, died two months later, on 4 August 1665, and the younger Charles succeeded as the 2nd Earl of Clancarty. The 2nd Earl died about a year later, on 22 September 1666, still an infant. At this point Callaghan became the 3rd Earl of Clancarty. However, he was then a monk in a monastery in France. Hearing of his accession to the earldom, he put his dynastic obligations above his religious ones. He left the monastery and returned to Ireland, where he left the Catholic Church and joined the Protestant Church of Ireland.
Marriage and children
Now styled Lord Clancarty, he married Elizabeth FitzGerald, daughter of George FitzGerald, 16th Earl of Kildare and his wife Joan Boyle. The FitzGeralds were an Old English family whose ancestor came to Ireland during the Norman invasion of that country. His wife has been described as "a fierce Protestant isolated in a Catholic family". The couple had two children:
Donough, became the 4th and last Earl of Clancarty.
Death and succession
Clancarty died on 21 November 1676, aged about 38. He seemed to have returned to his original Catholic religion just before his death. He was succeeded by his only son Donough, who was eight years old at the time. His widow married William Davys, chief justice, and died in 1698.
