4 Moved by these great evils, we thought it our duty, at the very outset of our Supreme Pontificate, to recall the last words of our Predecessor of illustrious and holy memory, and by repeating them once more to begin our own Apostolic Ministry; and we implored Kings and rulers to consider the floods of tears and of blood already poured out, and to hasten to restore to the nations the blessings of peace. God grant by His mercy and blessing, that the glad tidings the Angels brought at the birth of the divine Redeemer of mankind may soon echo forth as we His Vicar enter upon His Work: "on earth peace to men of good will" ( Luke ii. 14). We implore those in whose hands are placed the fortunes of nations to hearken to Our voice. Surely there are other ways and means whereby violated rights can be rectified. Let them be tried honestly and with good will, and let arms meanwhile be laid aside. It is impelled with love of them and of all mankind, without any personal interest whatever, that We utter these words. Let them not allow these words of a friend and of a father to be uttered in vain.
Source: Ad Beatissimi Apostolorum (Vatican.va)