Written: Written on December 21, 1917 (January 3, 1918)
Published: First published on March 6, 1959, in French in The Times Literary Supplement (London) No. 2975. First published in Russian on April 14–20, 1963, in Nedelya, Sunday supplement of Izvestia, No. 16
Dear Citizen Charles Dumas,
My wife and I recall with great pleasure the time we met you in Paris, rue Bonier. We are very grateful to you for the exchange of ideas and for the very accurate information on the socialist movement in France.
I very much regret that personal relations between us became impossible after such profound political differences divided us. Throughout the war I fought against the “national defence” trend, I always stood for a split, being convinced that that tendency was ruining socialism completely.
It goes without saying that I am writing this letter not as a member of the government but as a private individual.
Please accept our greetings, dear citizen, and best wishes from my wife and myself.
 On his arrival in Petrograd in December 1917, the French socialist Charles Dumas asked Lenin to receive him, mentioning that they were already acquainted. Lenin and Krupskaya met Charles Dumas in Paris, where they lived from December 1908 to June 10 (23), 1912.
During the First World War (1914–18), Dumas held social-chauvinist views, for which Lenin sharply criticised him in his work The Collapse of the Second International (see present edition, Vol. 21, pp. 209–10).