Her ambitious uncle Baron Le Poer, wanting to unite the Curraghmore and Dromana estates, arranged a marriage between Katherine and his own son and heir, John. On 20 May 1673, Katherine and John were married by
Gilbert Sheldon,
Archbishop of Canterbury in his chapel at
Lambeth Palace. She was three months short of her 13th birthday, and John was a boy of eight. That same year, her uncle was created 1st Earl of Tyrone and Viscount Decies by King Charles. Two years later, Katherine, who had not wanted to marry her eight-year-old cousin John Le Poer, appealed to the Archbishop to grant her an annulment on the grounds that she had not freely consented to the marriage. In March 1677, Katherine eloped and married an officer, Brigadier-General, Hon.
Edward Villiers, the son of George Villiers, 4th Viscount Grandison and Mary Leigh, and a cousin of
Barbara Villiers, the notorious and powerful mistress of King Charles. Following her clandestine marriage to Edward, there ensued a lengthy legal battle, which Katherine eventually won, due to the help from Edward's influential cousin, Barbara. Her marriage to Edward Villiers was thus declared legal and valid, while her uncle was forced to give back her lands and renounce the title of Viscount Decies. John Le Poer, her erstwhile husband later succeeded to the title of 2nd Earl of Tyrone in October 1690. An artist, who was a follower of court painter
Sir Peter Lely, painted her portrait between 1685 and 1690. The portrait, which is in a private art collection, shows Katherine to have been slender, with auburn hair and fair skin. Together Katherine and Edward had four children: • Mary Villiers (died 24 December 1725), married Brigadier-General Hon. William Steuart (d.1736) M.P., her stepfather's eldest nephew and adopted son; brother of
Admiral James Steuart M.P. •
Harriet Villiers (died 21 October 1736), married
Robert Pitt, by whom she had a son,
William Pitt, 1st Earl of Chatham • John FitzGerald Villiers, 5th Viscount Grandison, and 1st Earl Grandison (1684- 14 May 1766), married Frances Cary, by whom he had issue. • William Villiers Edward died in 1693, and she married her third husband,
General William Steuart, Commander-in-Chief of
Queen Anne's forces in Ireland, and a
Member of the Irish Parliament for County Waterford. This marriage was childless. Shortly after the death of her former father-in-law, Viscount Grandison, Katherine was granted the rank of Viscountess by
Royal Warrant issued by King
William III of England on 6 January 1700. == Death ==