Pope Pius XII
Mystici Corporis Christi §105
Mystici Corporis Christi: On the Mystical Body of Christ
105 And likewise, above all in the present crisis, it seems to Us not only opportune but necessary that earnest supplications should be offered for kings, princes, and for all those who govern nations and are thus in a position to assist the Church by their protecting power, so that, the conflict ended, "peace, the work of justice" under the impulse of divine charity may emerge from out this raging tempest and be restored to wearied man, and that holy Mother Church "may lead a quiet and peaceable life in all piety and chastity."We must plead with God to grant that the rulers of nations may love wisdom, so that the severe judgment of the Holy spirit may never fall on them: "Because being ministers of His Kingdom you have not judged rightly, not kept the law of Justice, nor walked according to the will of God; horribly and speedily will he appear to you; for a most severe judgment shall be for them that bear rule. For to him that is little, mercy shall be granted; but the mighty shall be mightily tormented. For God will not except any man's person, neither will he stand in awe of any man's greatness; for he made the little and the great, and he hath equally care of all. But a greater punishment is ready for the more mighty. To you, therefore, O Kings, these are my words, that you may learn wisdom and not fall from it."
Source: Mystici Corporis Christi (Vatican.va)