Catalina was the daughter of David Sarsfield, and niece of Dominick Sarsfield, 4th Viscount Sarsfield, both of whom had supported James II during the Williamite War in Ireland and had then left Ireland for France as part of the Flight of the Wild Geese. Part of the exiled Jacobite community, they served in Continental armies while hoping for the restoration of James II or his successors which would lead to the recovery of their lost estates in County Limerick. David was killed fighting at the Battle of Villaviciosa in 1710. Catalina was the eldest of his six daughters all of whom were born in Nantes.