In 1663 in Paris Pierre Chevalier published a book about Cossack uprising called "Histoire de la guerre des Cosaques contre la Pologne", which he dedicated to Nicolas Léonor de Flesselles, count de Brégy, who was an ambassador to Poland in 1645. In the dedication he described the meeting de Brégy had with Khmelnytsky in France, and group of Cossacks he brought to France to fight against Spain in Flanders. Chevalier also claimed that he himself commanded Cossacks in Flanders. Although in distant parts of the book Chevalier doesn't mention either Cossacks or Khmelnytsky even once. In his other writing, "Relation des Cosaques (avec la vie de Kmielniski, tirée d’un Manuscrit)", published the same year, which also contains a biography of Khmelnytsky, there is no mention about his or any other Cossacks stay in France or Flanders. Moreover first Chevalier book is the only source that mention such an event, there is not trace of it even in correspondence of count de Brègy. Although it is true that he was conducting a recruitment of soldiers in Poland for French army in years 1646-1648. In fact he succeeded and about 3000 of them travelled via Gdańsk to Flanders and took part in fights around Dunkirk. French sources describes them as "infanterie tout Poulonnois qu’Allemand". They were commanded by colonels Krzysztof Przyjemski, Andrzej Przyjemski and Georges Cabray. Second recruitment that shipped off in 1647 were commanded by Jan Pleitner, Dutch military engineer in service of Władysław IV and Jan Denhoff, colonel of Royal Guard. 17th century French historian Jean-François Sarasіn in his "Histoire de siège de Dunkerque" when describing participation of Polish mercenaries in fights over Dunkirk, notes that they were commanded by some "Sirot". Some historians identify him as Ivan Sirko, Cossack ataman.