Henry Hamilton, 2nd Earl of Clanbrassil

In May 1667 Clanbrassil married Lady Alice Moore, daughter of Henry Moore, 1st Earl of Drogheda and Hon. Alice Spencer, daughter of William Spencer, 2nd Baron Spencer of Wormleighton.[3] The marriage was contrary to the expectations of Clanbrassil's family. The couple lived an extravagant life between Killyleagh and Dublin. Their only child, James (born and died 1670) died in infancy and Clanbrassil's titles became extinct upon his death in 1675.[1]

In March 1674, Lady Clanbrassil is alleged to have convinced her husband to make a new will to ensure that Killyleagh passed to her, and not his cousins, upon his death.[3] This ran contrary to the entail in the first earl's will and Clanbrassil's mother warned her son against signing a new will, writing to him that he would die within three months if he did so.[2]

In January the following year, Clanbrassil died of suspected poisoning while in Dublin with Lady Clanbrassil.[4] The evidence that Lady Clanbrassil carried out the poisoning is circumstantial and inconclusive.[3] However, she had the body disembowelled and quickly buried in Christ Church Cathedral, Dublin, rather than in the family plot in Bangor, County Down. Lady Clanbrassil also had the new will, which she brought with her to Dublin, quickly proved by solicitors in the city without informing her dead husband's family.[2] Legal action was subsequently mounted by Clanbrassil's cousins against Lady Clanbrassil in an attempt to restore the original will and recover the estate; the matter was settled in February 1679.[3]