His great-grandfather Sir William Sarsfield had been Mayor of Dublin and was knighted for his service against the rebellion of Shane O'Neill in 1566.
He acquired two estates at Lucan Manor and Tully Castle in County Kildare, dividing the properties between two of his sons on his death.
Like the majority of the traditional Anglo-Irish population, he was raised as a Roman Catholic, as opposed to more recent arrivals who were generally Protestant.
The Catholic inhabitants, while proclaiming their loyalty to King Charles I, rose up against the Parliament of England and its allies in the Irish government in Dublin.
As a punishment he was expelled in June 1642 from the Parliament of Ireland (where he sat for Kildare Borough) and was attainted for high treason.
For Sarsfield, this meant the loss of both Tully Castle and Lucan Manor which he had recently inherited from his childless cousin.
After he secured support from influential figures such as Maurice Eustace and the Duke of Ormonde, the King agreed to restore Tully Castle to him.
[5] Theophilus Jones, who remained an influential figure and an officer in the Irish Army, refused to give up his ownership of Lucan Manor.
He was made Earl of Lucan by James II in reward for his services, particularly at the 1690 Siege of Limerick when he led a raid on the Williamite artillery train.