When Oliver Cromwell came to Ireland he issued an order on 20 September 1649 to the effect that Lord Power and his family were under his protection.
The Powers were pardoned in the Cromwellian Act of Settlement, but they were impoverished by the war, and in the spring of 1654 they received a weekly grant.
He succeeded to the peerage on the death of his father next year, and his kinsman James, Lord Annesley, was elected to fill his seat.
[1] The new Lord Power was made governor of the county and city of Waterford, and had also a company of foot; but the pay was often in arrear.
In May 1673 Power made a move to unite the Curraghmore and Dromana estates by marrying his ward and sister's daughter, Catherine Fitzgerald, to his eldest surviving son John.
Catherine was about twelve years old, and her cousin about seven, but Archbishop Gilbert Sheldon allowed a marriage ceremony to be performed before him in Lambeth Chapel.
[1] In October 1673 Lord Power was created Earl of Tyrone and Viscount Decies (a title formerly borne by the Fitzgeralds), in the Peerage of Ireland.
He was indicted for a treasonable conspiracy at the Waterford assizes in August 1679, and again in March 1680, Chief Justice John Keating presiding on both occasions.
After the accession of James II in 1685, he became a colonel of a regiment of foot, was made a privy councillor in May 1686, and in 1687 received a pension.
[1] Tyrone sat as a peer in the Patriot Parliament held on 7 May 1689, where the business included the attainder of most of the Protestant landowners.