 In the summer of 1939, before the occupation began, he saw the impending danger clearly enough to order the evacuation of many of the library's most valuable items.Quite soon after the occupation began, Cain was removed from his post by the Vichy government because he was Jewish and replaced by collaborationist Bernard Faÿ.In February, 1941, Cain was denounced in "Le Matin" and arrested.