In February 1782, he had been a delegate for Co. Antrim to the Ulster provincial Volunteer convention in Dungannon, and in November 1793 one of the five Co. Antrim delegates to the national Volunteer convention in Dublin that sought to build on the legislative independence secured for Ireland the previous year, with parliamentary reform.[3]
In 1793, raised to the Peerage of Ireland as Baron O'Neill, of Shane's Castle in the County of Antrim.[4] In 1795 he was further honoured when he was made Viscount O'Neill, of Shane's Castle in the County of Antrim, in the Irish peerage.[5]