18 The evil results of the Great War, as they affect the spiritual life, have been felt all over the world, even in out-of-the-way and lonely sections of far-off continents. Missionaries have been forced to abandon the field of their apostolic labors, and many have been unable to return to their work, thus causing interruptions to and even abandonment of those glorious conquests of the Faith which have done so much to raise the level of civilization, moral, material, and religious. It is quite true that there have been some worthwhile compensations for these great spiritual misfortunes. Among these compensations is one which stands out in bold relief and gives the lie to many ancient calumnies, namely, that a pure love of country and a generous devotion to duty burn brightly in the souls of those consecrated to God, and that through their sacred ministry the consolations of religion were brought to thousands dying on the fields of battle wet with human blood. Thus, many, in spite of their prejudices, were led to honor again the priesthood and the Church by reason of the wonderful examples of sacrifice of self, with which they had become acquainted. For these happy results we are indebted solely to the infinite goodness and wisdom of God, Who draws good from evil.
Source: Ubi Arcano Dei Consilio (Vatican.va)