Ó Derrig was active in County Kildare in the early 1650s, in the aftermath of the Irish Confederate Wars.
A court-martial held in Kilkenny on 23 September 1653 found Murtagh Cullen and his wife guilty of sheltering Ó Derrig.
In July 1654, he led his band of outlaws and killed an Irishman working as a constable for the English in Timolin, County Kildare.
In March 1655, he captured and subsequently hanged eight surveyors of Sir William Petty as accessories to a gigantic scheme of ruthless robbery.
In the autumn, Ó Derrig's wife was one of thirty-seven people rounded up and transported via a frigate of Wexford to Barbados, arriving in May 1656.