How French mathematicians learned about what happened to their Polish colleagues during WW2

International audienceThis article presents an exchange of letters between Wacław Sierpiński and Paul Montel during the year 1945. This correspondence, translated here into English, provides insight into how and in what form the French learned about the dramatic fate of many Polish mathematician colleagues during the war. We also give a short biography of the two protagonists, as well as some facts about the mathematicians mentioned in the letters