Iseult was born on 6 August 1894, the illegitimate daughter of Maud and her then married French Boulangist lover Lucien Millevoye. She was conceived in the mausoleum of her late brother, Georges Silvère (1890–1891) who died of meningitis, in an attempt by her parents to reincarnate their dead and still adored infant. She was educated at a Carmelite convent in Laval, France; when she returned to Ireland she was referred to in public as Maud's niece rather than daughter.
Iseult was widely considered a great beauty, but temperate and able to speak her mind. She attracted the admiration of literary figures including Ezra Pound, Lennox Robinson and Liam O'Flaherty. Her most famous association was with William Butler Yeats, who had long been in love with her mother. In 1916, while in his fifties, Yeats wooed and proposed to the 22 year-old Iseult, whom he had known since she was 4. Although she refused, he became the closest she would have to a father figure. Her relationship with her stepfather John MacBride had long been tainted due to rumours of abuse on his part. Yeats wrote to Lady Gregory in January 1905, the month MacBride and Maud separated, that he had been told MacBride had molested Iseult, who at that time was going on 11 years old.
In 1913, Iseult met Rabindranath Tagore. Inspired by his poetry, she began to learn Bengali in 1914. She was tutored by Devabrata Mukerjea. Together, in France, they translated some of Tagore's The Gardener into French directly from the Bengali. Tagore left it to Yeats' discretion to decide the merit of the work, but Yeats did not feel sufficiently bilingual in French to judge them. The translations were never published.
In 1920, she eloped to London with the Irish-Australian writer, Francis Stuart. Under duress from both their parents, the couple later married. Their first child, Dolores, died in 1921 of spinal meningitis while three months old. The couple had two other children, Ian and Catherine.
When Maud Gonne died in 1953, Iseult was not acknowledged as her mother's daughter in her will. Iseult died a year later.
- Bolger, Dermot. "A life less ordinary: The tale of Maud Gonne's daughter". The Sunday Business Post, 26 December 2004. Retrieved on 20 June 2007.
- Amanda French, "A Strangely Useless Thing: Iseult Gonne and Yeats," Yeats Eliot Review: A Journal of Criticism and Scholarship 19:2 (2002): 13-24
- Foster, 331-2
- Deirdre Toomey, ‘Stuart , Iseult Lucille Germaine (1894–1954)’, Oxford Dictionary of National Biography, Oxford University Press, 2004
- R. F., Foster. W. B. Yeats: A Life, Vol. I: The Apprentice Mage. New York: Oxford UP, 1997. ISBN 0-19-288085-3.
- Letters to W.B. Yeats and Ezra Pound from Iseult Gonne: A Girl That Knew All Dante Once; Palgrave Macmillan, 2004; ISBN 1-4039-2134-2, ISBN 978-1-4039-2134-5
- Amanda French, "A Strangely Useless Thing: Iseult Gonne and Yeats," Yeats Eliot Review: A Journal of Criticism and Scholarship 19:2 (2002): 13-24.