Chambrun was a lawyer at the
Court of Appeals of Paris and the
New York State Bar Association. 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. After the
Liberation of France and the consequent fall of Laval's
collaborationist government, Chambrun was a defender of Laval: 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. In 1942, Chambrun had been named on a list of French collaborators with Germany to be killed during the war or tried after it. By 1947, Chambrun officially applied for a US passport. Meanwhile, Chambrun and his wife devoted their energies over the following decades to the cause of his rehabilitation in the eyes of history. 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. 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." 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." 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. Wertheimer settled the case, and Chanel became a millionaire as a result. Additionally, Chambrun was hired by
Somerset Maugham's daughter to prove that she was indeed his daughter. Chambrun served as the chairman of
Baccarat, the
crystal manufacturer, from 1960 to 1992. ==Personal life and death==