[1] He was descended from Jean d'Alesso (1513–72), first known seigneur of Éragny, Val-d'Oise, treasurer of the constable Anne de Montmorency (1492–1567) and adviser of King Charles IX of France (1550–74).
[1] An embassy from Siam led by Ok-khun Chamnan was dispatched to Louis XIV of France and Pope Innocent XI by the Siamese King Narai in 1688.
The Siamese mission was accompanied by the Jesuit Father Guy Tachard and the French envoy extraordinary to Siam, Simon de la Loubère.
[4] Two weeks later a military treaty was signed that designated d'Eragny as captain of the palace guard in Ayutthaya and inspector of French troops in Siam.
In 1711 Alexandre François d'Alesso d'Éragny married Catherine Pocquet, daughter of an important settler of Basse-Pointe, captain of militia and member of the sovereign council of Martinique.
[11] His descendant Claire de Duras (1777–1828) was the heiress to an immense fortune in Martinique, where she took refuge with her mother (née d’Alesso d’Éragny) during the French Revolution.
Claire was married to Amédée de Durfort, Duke of Duras, and became a successful novelist during the Bourbon Restoration, with work that explores questions of racial and sexual equality.