He was a son of Baroness Anne Hélène Amélie Marie von Krüdener (1830–1859) and Arthur Jules Philippe, Count of Fontenilliat (1822–1900).
[2] His father, a Knight of the Order of the Holy Sepulchre, served as Secretary to the French Legation in Sweden in 1853.
Shortly after their marriage, he was forced to resign because "of a scandal created by a girl named Odette, who accused him of having borrowed money of her.
[10] In 1902, while in Carbet, a suburb of Saint-Pierre, Martinique, Fontenilliat witnessed the 1902 eruption of Mount Pelée which killed 28,000 people.
[13][14] Among her siblings were Alva Erskine Smith, the first wife of William Kissam Vanderbilt (parents of Consuelo Spencer-Churchill, Duchess of Marlborough), and Mary Virginia Smith, the first wife of banker Fernando Yznaga (brother of Consuelo Montagu, Duchess of Manchester).
[20] He married, secondly, Mary Josephine (née Livingston) Blanc de Lanautte d'Hauterive (1854–1937) in Paris on 23 July 1913.