Daniel O'Brien, 3rd Viscount Clare

Daniel was born the eldest son of Connor O'Brien and his wife Honora O'Brien. His father was the 2nd Viscount Clare. His father and his mother were from different branches of the O'Briens, an important Gaelic Irish dynasty that descended from Brian Boru, medieval high king of Ireland.[1] His mother's family were the O'Briens of Duagh.

He was appointed commander of a newly raised regiment of foot, Clare's Regiment of Foot, an Irish regiment in the Dutch States Army, on 8 August 1674. He was replaced within twelve months by Sir John Fenwick. From July 1751 this regiment was known as the 5th Regiment of Foot.

During the War of the Two Kings, Clare served with the Jacobite Irish Army loyal to James II. He was the commander of Clare's Dragoons regiment which he led against William of Orange at the Battle of the Boyne and later exile in France as part of the Flight of the Wild Geese.

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

Daniel and Philadelphia had three children:

1. Honora O'Brien
2. Daniel (died 1693)
3. Charles (1673–1706)

In 1670 O'Brien succeeded his father as the 3rd Viscount Clare.[6] In 1689 James II of England appointed Clare, as he was now, together with Boileau as joint governors of Cork.[7] On the 11 August Clare emprisoned the Protestants of the city in St Peter, Christchurch, and the courthouses.[8] They were later detained in the castles of Blarney and Macroom.[9][10] In 1690 Clare fought for James at the Battle of the Boyne.[11]

Daniel died in 1691. He was outlawed on 11 May 1691.[12]