Catherine (died March 1834), daughter of Stephen Moore, 1st Viscount Mount Cashell and Alicia Colville.
When Viscount Kingsborough succeeded his father as Earl of Kingston in 1799 and triggered a by-election for County Roscommon, Mahon saw an opportunity.
With their help, Mahon won the support of the Catholic and independent interests of the county for his eldest son Thomas, who had recently defended Carlow during the Rebellion of 1798.
[3] The stratagem worked: Stephen voted for the Union, and on 30 July 1800, Maurice was raised to the Peerage of Ireland as Baron Hartland, of Strokestown in the County of Roscommon,[4] as a reward for his support.
[2] Stephen continued to support government on Hartland's instructions, his object being to secure a further promotion to a viscount in the Irish peerage.