William FitzWilliam, 3rd Viscount FitzWilliam
William FitzWilliam, 3rd Viscount FitzWilliam (c.1610–1670) was an Irish nobleman of the Stuart era. He fought on the Royalist side during the English Civil War, but later made his peace with the Cromwellian regime. In his later years he openly professed the Roman Catholic faith.
He was born at Merrion Castle, at present-day Mount Merrion, Dublin, the youngest son of Thomas FitzWilliam, 1st Viscount FitzWilliam and Margaret Plunkett, daughter of Oliver Plunkett, 4th Baron Louth. The FitzWilliam family were first recorded in Ireland about 1210, and by the seventeenth century had become among the largest landowners in Dublin. They had a record of loyalty to the English Crown, and the viscountcy was conferred on Thomas in 1629 by Charles I in recognition of his good services. The title did not come cheap since the Crown expected financial help in return, and the estates were mortgaged in the 1630s to cover the cost of the family's gifts to the Crown.
Civil War and Restoration
As a young man William appears to have lived very much in the shadow of his brother Oliver FitzWilliam, 1st Earl of Tyrconnell. When Oliver became a Colonel in the French Army, William was his lieutenant. Both gained the trust of Charles I of England, and while Oliver returned to fight in Ireland, William became Governor of Whitchurch and Lieutenant General for Shropshire.
When the Royalist cause became hopeless, Oliver and William both made their peace with Oliver Cromwell; in 1655 after the deaths of their father and eldest brother, a portion of the family lands were restored to them. Before the fighting became serious, William and his wife and family had lived at Dundrum Castle, but they were driven out in 1642, returning again in 1646. In about 1652, the Fitzwilliams left Dundrum and did not live there again. Their later home was Simmonscourt Castle, where they were living shortly after the Restoration of Charles II
In 1667 on Oliver's death William became 3rd Viscount, as Oliver had no children, and the next brother Christopher had also died leaving an only daughter, so that the Earldom died with Oliver; but William enjoyed the title for only a few years. He seems to have preferred to live in Dublin City rather than at Merrion, which was then some distance from the city, and died at his town house in the parish of St. Nicholas Within, near Christ Church Cathedral.
Encouraged perhaps by Charles II's well-known inclination to the Catholic Church, which he entered on his deathbed, William, despite the Penal Laws, openly practiced his Roman Catholic faith. At his death he was attended by several Catholic priests, and though like his brother Oliver he was buried in Donnybrook Church the burial service was conducted according to the Catholic rite. His son and heir Thomas was also an open Catholic, while his daughters married into untitled Catholic families rather than the Protestant nobility.
- Thomas FitzWilliam, 4th Viscount FitzWilliam
- Mary, who married John Browne of Clongowes Wood, County Kildare
- Rose, who married Christopher Malpas of Winston
- Margaret, who married James Crawley
- Catherine, who married Nicholas Netterville
- Dorothy, who married Thomas Meagher.