21 The circumstances surrounding the mission of St. Francis to La Chablais are well known to you, Venerable Brothers, for when, towards the close of 1593, as we learn from history, the Duke of Savoy concluded a truce with the inhabitants of Berne and Geneva, nothing was thought more important in order to reconcile the population to the Church than to send them zealous and learned preachers who, by the persuasive force of their eloquence, would slowly but surely win back these people to their allegiance to the Faith.
Source: Rerum Omnium Perturbationem (Vatican.va)