Chambrun was a great-great-grandson of Lafayette.[5][6] As a result, he was both a French and US. citizen.[6] His US citizenship was questioned by members of the US House of Representatives in 1942 for his support of his father-in-law, Pierre Laval.[7]
Chambrun was a lawyer at the Court of Appeals of Paris and the New York State Bar Association.[5] By 1935, he helped establish a Franco-American cultural center in New York City to promote bilateral relations. The center was aimed at students and businessmen.[8]
When the Second World War broke out, Chambrun served as a captain, but with the collapse of France looming by mid-May 1940, French Prime Minister Paul Reynaud sent Chambrun as a special emissary to Washington to stiffen President Roosevelt's resolve to help the Allies. Between his first meeting with Roosevelt on 16 June and his last on 1 August, Reynaud's government had fallen. Later that year, Chambrun published the book I Saw France Fall, which helped to alert American opinion about the fate of his country.
Father-in-law wants a big trial which will illuminate everything, if he is given time to prepare his defence, if he is allowed to speak, to call witnesses and to obtain from abroad the information and documents which he needs, he will confound his accusers.[9]
The Chambruns threw themselves into the task of assisting Laval in his defense before the High Court of Justice. After Laval's sentence and execution in October 1945, Chambrun was put on police watch in Paris on the suspicion that he may have helped the Nazis during the war.[10] In 1942, Chambrun had been named on a list of French collaborators with Germany to be killed during the war or tried after it.[11] By 1947, Chambrun officially applied for a US passport.[12][13]
Meanwhile, Chambrun and his wife devoted their energies over the following decades to the cause of his rehabilitation in the eyes of history.[14] For example, he wrote a letter to President Dwight Eisenhower in which he objected to his characterisation of Laval as "Hitler's most evil puppet" in his 1948 memoir entitled Crusade in Europe.[15][16] Chambrun based his argument on another book, authored by Spanish Foreign Minister Ramón Serrano Suñer, in which the latter quoted Hitler describing Laval as "no better than De Gaulle."[15] By 1949, Eisenhower agreed to remove the passage from subsequent reprints.[15][16] A decade later, in 1959, his wife wrote the foreword of Tout ce qu'on vous a cache, a book based on "German secret files" authored by Jacques Baraduc, Laval's lawyer.[17] The book attempted to show that Laval "refused repeatedly to yield to German demands for a reduction in the number of United States agents in French North Africa and a limitation on their activity."[17]
In 1969, Chambrun made an appearance in Marcel Ophüls's documentary on collaboration between the Vichy government and Nazi Germany during World War II, The Sorrow and the Pity (Le chagrin et la pitié). Chambrun wrote three books on the subject between 1983 and 1990. The Chambruns set up a foundation, the Josée and René de Chambrun Foundation, which collected documents on Laval for publication by the Hoover Institution. After Laval's death, the Chambruns brought flowers to his grave every 15 October to commemorate the day that he was executed.[18]
After World War II, Chambrun was hired by King Peter II of Yugoslavia when the latter filed for divorce in 1953;[19] the couple reconciled two years later. He represented the fashion designer Coco Chanel when she sued manufacturer Pierre Wertheimer to regain the marketing rights to her perfume, Chanel No. 5.[20] Wertheimer settled the case, and Chanel became a millionaire as a result.[20] In 1970 Chambrun defended Greek shipping magnate Stavros Niarchos over false allegations that he killed his ex-wife, Eugenia Livanos.[21] Additionally, Chambrun was hired by Somerset Maugham's daughter to prove that she was indeed his daughter.[22]
Upon Louis de Lasteyrie's death in 1955, Chambrun discovered the large cache of documents in the attic of the castle[29] and founded a private museum about Lafayette.[30] News of his discovery brought many historians to his door, but Chambrun denied access, except to André Maurois whom he authorized to write a biography of Adrienne de Lafayette.[28][29][31] Chambrun produced a book by using the documents that he had discovered; they covered the period of 1792–1797, when Lafayette was in an Austrian prison. He organized and described the family archives, a collection dating from 1457 to 1990. The papers were microfilmed at La Grange in 1995 and 1996, for the Library of Congress.[32] It took two years and several microfilm teams from the Library of Congress to film the 50,000 pages.[33] There are now two major "Lafayette collections" in the world: one is at the Fondation de Chambrun; the other, originally assembled by Elie Fabius, at Cornell University Library. Chambrun purchased a sword used in battle by Lafayette in 1976,[34] outbidding the Smithsonian Institution.[35]
Chambrun, René de (1932). Les Emprunts sur titres et le marché de l'argent à New-York. Paris: Rousseau et Cie. OCLC459185128.
Chambrun, René de (1940). I saw France fall. Will she rise again?. New York: W. Morrow & Co. OCLC395042.
Chambrun, René de (1964). Baccarat's first two hundred years of history, 1764-1964. Paris: Corbeil-Essonnes. OCLC35184101.
Chambrun, Adolphe de; Corcelle, Marie Hélène Marthe de (1976). Chambrun, René de (ed.). Un Français chez les Lincoln : lettres inédites adressées pendant la guerre de Sécession. Paris: Librairie académique Perrin. ISBN9782262000387. OCLC3868356.
Chambrun, René de (1977). Les prisons des La Fayette : dix ans de courage et d'amour. Paris: Perrin. ISBN9782262000738. OCLC3670435.
Chambrun, René de (1986). France during the German occupation, 1940-1944 : summaries and important selections from statements on the government of Maréchal Pétain and Pierre Laval. A bibliographical supplement. Stanford, California: Hoover Institution Press. ISBN9780817983727. OCLC13821262.
Chambrun, René de (1988). Les 2,600,000 otages français d'Hitler, 1940 : la France, puissance protectrice de ses prisonniers. Paris: Editions France-Empire. ISBN9782704805983. OCLC21762580.
Chambrun, René de (1993). Mission and betrayal, 1940-1945 : working with Franklin Roosevelt to help save Britain and Europe. Stanford, California: Hoover Institution Press. ISBN9780817992217. OCLC26722920.
^"Daughter of French Premier Weds Count Rene de Chambrun". The Winnipeg Tribune. Winnipeg, Canada. 19 August 1935. p. 6. Retrieved 2 August 2016 – via Newspapers.com. The bridegroom is a nephew of Nicholas Longworth, speaker of the house of representatives and husband of the former Alice Roosevelt.
^Allen, Robert S.; Pearson, Drew (6 June 1942). "The Washington Merry-Go-Round". The Ogden Standard-Examiner. p. 4. Retrieved 1 August 2016 – via Newspapers.com. Members of congress are toying with the idea of removing honorary U. S. citizenship from Laval's son-in-law, Count Rene de Chambrun. As a descendant of Lafayette, de Chambrun automatically is entitled to U. S. citizenship, but close affinity with papa-in-law may remove it...
^Naud, Albert, Pourquoi je n'ai pas défendu Pierre Laval, Paris: Fayard 1948
^"French Await Purge for Aiding Nazis". The Salt Lake Tribune. Salt Lake City, Utah. 4 December 1945. p. 4. Retrieved 2 August 2016 – via Newspapers.com. The young Chambrun, who has been on police watch for months, was said to have disappeared early this week from his Paris residence.
^Pearson, Drew (2 January 1947). "The Washington Merry-Go-Round". Freeport Journal-Standard. Freeport, Illinois. p. 8 – via Newspapers.com. One thing that gripes heroic European leaders of the underground is the way collaborationists are now welcomed to the U.S.A. Rene de Chambrun, son-in-law of traitor Pierre Laval, is now applying for a passport, while Karol Sidor, one of Czekaslovakia's collaborationists, has already been granted one...
^Pearson, Drew (2 January 1947). "The Washington Merry-Go-Round". The Delta Democrat-Times. Greenville, Mississippi. p. 4. Retrieved 2 August 2016 – via Newspapers.com. One thing that gripes heroic European leaders of the underground is the way collaborationists are now welcomed to the U.S.A. Rene de Chambrun, son-in-law of traitor Pierre Laval, is now applying for a passport, while Karol Sidor, one of Czechoslovakia's collaborationists, has already been granted one...
^Wallenstein, Marcel (2 November 1961). "The Lafayettes--Model Wife, Heroic Spouse". The Kansas City Times. Kansas City, Missouri. p. 48. Retrieved 1 August 2016 – via Newspapers.com. The Chambruns have given much of their time since World War II in trying to clear the reputation of Laval, Hitler's French collaborator, who was executed by a French firing squad for his crimes after the defeat of the Nazis.
^"Laval is Executed After 11th Hour Suicide Attempt". Middletown Times Herald. 15 October 1945. p. 10. Retrieved 2 August 2016 – via Newspapers.com. She was staying at the home of her daughter, Jose de Chambrun, wife of Count Rene de Chambrun, in Place de Palais-Bourbon.