The article is devoted to the history of the restoration of the integrity of the previously dispersedpersonal archive of Gilbert Romme (1750-1795), a prominent French revolutionary of the 18th century, by the Russian historian, Grand Duke Nikolai Mikhailovich. Working on the biography of Pavel Stroganov (1772-1817), an outstanding state and military figure of Russia of the epoch of Alexander I, Nikolai Mikhailovich tried to collect scattered in France and Russia papers of Romme, who had served before the Revolution as tutor in the Stroganov house. The Grand Duke, with the help of the French historians Frederic Masson and François Boyer, succeeded in the restoration of this seemingly lost unique collection of archival sources concerning the French and Russian history of the 18th century.