The article deals with the analysis of one of the earliest French demonological tracts – Flagellum maleficorum, published for the first time in Lyon about 1462. Its author, Pierre Mamoris, professor of theology at the University of Poitiers, linked the spread of witchcraft and magic in France with the time of the Hundred Years War and, in particular, with the pernicious impact of the English invaders on the population of the Kingdom. The article analyzes the system of evidences used by P. Mamoris to justify his very special point of view, his personal memories and stories of eyewitnesses about the cases of witchcraft which took place in Poitou. The author puts forward her hypothesis on how a similar concept of cultural influence could arise at the end of the XVth century and how it was connected in France with a subsequent perception of the English Protestants as heretics and servants of the devil.