Fr. Vallet had founded the Parish Cooperators of Christ the King in 1922 and after his death in 1947 his priestly collaborators carried on his work. The key preacher at the chief house of the Parish Cooperators in France, was Fr. Ludovic Marie Barrielle. When the changes of Vatican II swept through the Church demanding aggiornamento and change at every level, Fr. Barrielle held firm. Fr. Vallet had been clear: nothing must be changed or else all the fruit would be lost. Though Fr. Barrielle himself held firm, the work of the Parish Cooperators gradually died out. Hearing of the work of Archbishop Lefebvre in the 70s, Fr. Barrielle volunteered his services and the Archbishop, in need of experienced priests, accepted.
      Moving to the Society’s chief seminary in Econe, Switzerland, Fr. Barrielle filled perfectly the office of spiritual director. His role was that of the much needed wiser, more experienced and older priest who helped prepare the young seminarians for the difficult task of the priesthood in the modern world. He counseled, encouraged, and taught them the principles of Saint Ignatius. Most importantly, he gave them the 5-Day Spiritual Exercises after the divinely inspired pattern given him by Fr. Vallet.
      Occasionally, when a veteran retreatant would call up for Fr. Barrielle to organize a retreat, Fr. Barrielle would bring along a seminarian and teach him the "ropes." Besides this practical knowledge, in response to the perennial question of the seminarian: "How will I go about the work of saving souls in this world?", he wrote two books: Letter to the Priests of Tomorrow, #1 and Letter to the Priests of Tomorrow, #2. In these books Fr. Barrielle laid down precise instructions for the preaching of the 5-Day Retreats.
      When Fr. Barrielle died in 1983, he had firmly planted the Ignatian Exercises in the Society of Saint Pius X which at that time numbered a little over 100 priests. Those priests in turn became the "veterans" and "old-timers" who continue to teach the new recruits the method and efficacy of the Spiritual Exercises. As a general rule, every deacon of the Society of Saint Pius X is required to preach an Ignatian Retreat to ensure his facility in this form of Apostolate before he is dispatched to his mission as a priest.
      To this day, the 5-Day Retreats are the workhorse of the Society of Saint Pius X in terms of obtaining profound conversions and dedicated soldiers of Jesus Christ. A tradition begun in the Church with Saint Ignatius, adapted to the modern world by Fr. Vallet, handed down to the Society of Saint Pius X by Fr. Barrielle, the Retreats are still available to souls who possess a desire to save their souls and to do something more for Christ.