William Sarsfield (died 1675)

William Sarsfield was an Irish landowner of the seventeenth century. He was the elder brother of the Jacobite soldier Patrick Sarsfield and was married to Mary Crofts, a woman believed to have been an illegitimate daughter of Charles II.

He was of both Gaelic (he was a grandson of Rory O'Moore) and Old English descent. The Sarsfields had come to Ireland during the Norman conquest of the twelfth century and had become leading figures of The Pale. His great, great-grandfather Sir William Sarsfield served as Mayor of Dublin and purchased an estate at Lucan Manor. Like most of the Old English community, the Sarsfield remained Roman Catholic. His father Patrick Sarsfield senior took part in the Irish Rebellion of 1641, but like other Irish Confederates continued to swear allegiance to Charles I. He assisted royal forces against the English republicans during the Cromwellian conquest of Ireland, and lost his estates as a consequence.

After the Restoration, the family sought to have their former lands recovered. Although Patrick Sarsfield was found guilty by the court of claims in involvement in the 1641 rebellion, this did not alter his sons right's to inherit him. As heir William took possession of Tully Castle while, following intervention from Charles II to whom he was a de facto son-in-law, it was agreed that he would gain ownership of Lucan Manor following the death of its occupant Theophilus Jones. In the event Jones outlived William by a decade.

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