The Du Mesgnil genealogy website documents the family’s descent from Jean I du Mesgnil, a 15th-century Champagne nobleman, and traces its branches, alliances, heraldry, and descendants. It follows the family from its estates in Champagne to branches established on the island of Bourbon, now Réunion, and presents genealogical tables alongside historical notes on people, places, and related families. Visitors can explore family lineages, recent additions, prominent surnames, coats of arms, photographs, individuals, dates, and locations.

The site highlights the principal branches descended from Jean’s grandson Nicolas du Mesgnil, including the lines of Engente, Arrentières, Bourbonne, and Chambourg. It describes the Engente branch’s move to Bourbon around 1776 and notes descendants such as aviator Roland Garros, while the Arrentières branch includes figures such as former French prime minister Raymond Barre. The collection also covers allied families from Champagne and elsewhere, drawing on historical records and noble genealogies. Its armorial material features the traditional Du Mesgnil shield: three silver horizontal bars on a blue field.