See this online text:

  • Christi Matri: Encyclical on Prayers for Peace during October, by Blessed Pope Paul VI (September 15, 1966). May be read online at the Holy See; on this page of Blessed be God; and at IntraText (with the heading ‘Introduction’ added).

On Rosary Sunday in the Roman Rite, and on the Feast of the Intercession of the Holy Theotokos in the Byzantine Rite.

From the text:

“Those in whose hands rests the safety of the human race should realize that in this day and age they have a very grave obligation in conscience. Mindful of their own nation, of the world, of God and history, let them examine their own consciences… 

“And so during the month of October, dedicated to Our Lady of the Rosary, prayers and petitions should be increased, so that through her intercession the dawn of true peace may shine forth to men…”