Jean Cruppi died during the 1914-18 war as a Lieutenant in the French army, and Ravel dedicated to him posthumously the Fugue in Le tombeau de Couperin.
He was known to the composer principally through his mother, Mme Cruppi, who was herself a musician, and who had been energetic in getting Ravel's opera L'heure espagnole its first performances at the Opéra-Comique. (Ravel dedicated the work to her, and also his song Noël de jouets.) His correspondence with her, reporting on his travels and his musical projects, shows him to have been on close terms with her and her family (Orenstein,  Letter 24)
Jean Cruppi's father, also Jean (1855 - 1933), was a prominent politician who served as a Député for 25 years. He held various ministerial posts, including Education (1907), Commerce et l'Industrie (1908), Affaires Etrangères (1911), and from June 1911 to January 1912 he was Ministre de la Justice.
Jean Cruppi, père