Daniel O'Brien, 3rd Viscount Clare

Daniel was born roughly about 1620, probably at Carrigaholt Castle, County Clare, his parents' habitual residence. He was the only son of Connor O'Brien (c. 1605 – 1670) and his wife Honora O'Brien.^[3] At the time of his birth, his father was the heir apparent of his grandfather, O'Brien of Carrigaholt, who was a younger brother of Donogh O'Brien, 4th Earl of Thomond. His father's family was the senior branch of the O'Briens, a Gaelic Irish dynasty that descended from Brian Boru, medieval high king of Ireland.^[4]

His mother's family were the O'Briens of Duagh, County Kerry, a cadet branch of the O'Briens that descended from Donal, younger brother of Donough O'Brien, 2nd Earl of Thomond.^[5] Daniel was one of six siblings, who are listed in his father's article.

O'Brien lived as a young man through the Irish Rebellion of 1641, the Irish Confederate Wars, and the Cromwellian conquest of Ireland, probably fighting under the command of his father and grandfather. He probably was the "Daniel O'Bryan" who was given as hostage to General Edmund Ludlow at the surrender of Ross Castle on 27 June 1652.^[6]

He went with his father and grandfather into French exile and seems to have been a courtier at Charles II's court in exile. At the Restoration in 1660 he returned to England or Ireland with his father and grandfather. On 11 July 1662 Charles II created his grandfather Baron Moyarta and Viscount Clare.^[7] The honour was intended for him, Daniel,^[8] into whose hands the estate was directly conveyed.^[9] His grandfather died in 1663^[10] or in 1666, and his father succeed as 2nd Viscount and he gained the courtesy title of Baron Moyarta.

He married Philadelphia Lennard, sister of the Thomas, Earl of Sussex.

Daniel and Philadelphia had three children:

1. Honora O'Brien
2. Daniel (died 1693), 4th viscount died unmarried in French exile^[11][12]
3. Charles (1673–1706), 5th viscount, who died of wounds received at the Battle of Ramillies fighting for the French^[13]