Complex sentence: James Dillon, 3rd Earl of Roscommon (c.1605--1649) was one of the ten persons named in Act for the Settlement of Ireland 1652 as leaders of the Royalist forces in Ireland, thus rendering their estates liable to forfeiture.
Split into simpler sentences: James Dillon, 3rd Earl of Roscommon (c.1605--1649) was an Irish peer. He was one of the ten persons named in Act for the Settlement of Ireland 1652 as leaders of the Royalist forces in Ireland, thus rendering their estates liable to forfeiture.