In 1943 while under Italian wartime occupation, Schneersohn founded a documentation center at his home in Grenoble with representatives from 40 Jewish organizations.
Schneersohn had a brother, Dr. Fishel Schneerson[8] and three sons: Boris,[9] Arnold, and Michel,[10] who were mobilized as reserve officers in the French Army.
[13] He founded the documentation center CDJC in 1943 while in Grenoble, moved it to Paris, and remained director until his death.
Isaac Schneersohn and Léon Poliakov got back to Paris at the time of the insurrection of August 1944.
[15] On January 27, 2005, the occasion of the 60th anniversary commemoration of the liberation of the Auschwitz concentration camp, Schneersohn was remembered by Éric de Rothschild, President of the Mémorial de la Shoah,[16] by the Mayor of Paris, Bertrand Delanoë,[16] and by President of the French Republic, Jacques Chirac.
[13] On October 8, 1958, the future Nobel Peace Prize laureate René Cassin presented him with the Cross of the Knight of the Legion of Honor.
[13] In Paris, he was close to Rabbi David Feuerwerker, who took part in the annual ceremonies at the CDJC on numerous occasions in the presence of the authorities.
Without knowing whether he or any of them would even survive the war, Schneersohn was motivated by a desire to accumulate and preserve materials and to write about everything that was happening, as building blocks for historians who would come later.
[20][21] The documentation center was organized with a seven-member management committee consisting of two representatives of the Consistory (Consistory (Judaism)) (Consistoire central), two representatives of the Fédération des sociétés juives de France [fr], one from the World ORT, and one from the rabbinate, with Schneersohn presiding.