Sodom and Gomorrah IV pp 142-62

Hesse

p 142 | Grand Duke of Hesse (brother-in-law of Princesse de Guermantes)
p 142 | Crown Prince of Sweden must have been Oscar Gustaf Adolf (King Gustav), who acceded in 1907, on the death of his father Oscar II.
p 142 | Empress Eugénie was a Dreyfusist: Eugénie (1826-1920), the widow of Napoleon III, was indeed a Dreyfusard (Sturrock)
p 143 | Bourg l’Abbé, Bois-le-Roi, and the like: in the Middle Ages, the titles of local dignitaries, such as Abbé, or Abbot, could become part of a place-name.
p 143 | The Restoration was the period immediately following the fall of Napoleon and the First Empire.
p 145 | Jean-Marc Nattier (French painter, 1685-1766).

Duchesse de Châtrearoux

p 147 | Hubert-Joseph Henry (1846-98), French army officer & creator of the forged Henry document. And here is a great educational Dreyfus website, in English.
p. 159 | Marie-Jean-Léon Lecoq, Marquis d'Hervey de Saint-Denis, (French sinologist, 1822-92).

p 162 | Mgr. Félix Dupanloup, French ecclesiastic, 1802-78.

p 162 | Paul Boniface "Boni" de Castellane, the marquis de Castellane (1867-1932) and his brothers Jean and Stanislas de Castellane.

p 162 | Prince de Sagan