Pope Paul VI
Mense Maio §6
Mense Maio: On Prayers During May for Preservation of Peace
6 The second reason for our appeal stems from the present state of international affairs, which, as you well know, Venerable Brothers, is extremely troubled and uncertain. The supreme benefit of peace is again being placed in jeopardy. Today we see tensions worsening gravely between nations in certain parts of the world, as if no lesson had been learned from the bitter experiences of the two world wars which caused so much bloodletting in the first half of this century. Once again we see men risking recourse to arms instead of negotiating to settle disputes between opposing viewpoints. Thus the inhabitants of entire nations are subjected to unspeakable sufferings occasioned by uprisings, secret and treacherous warfare, and outright battles. These activities grow more frequent and more bitter each day, and could at any time spark a new and terrible war.
Source: Mense Maio (Vatican.va)