Padre Pio's letter supporting Humanae Vitae, perhaps the most controversial encyclical ever, released 43 years ago this summer

Pope Paul VI had this letter published in L'Osservatore Romano. 

Your Holiness:

Availing myself of Your Holiness' meeting with the Capitular Fathers, I unite myself in spirit with my Brothers, and in a spirit of faith, love and obedience to the greatness of Him whom you represent on earth, offer my respectful homage to Your August Person, humbly kneeling at Your feet.

The Capuchin Order has always been among the first in their love, fidelity and reverence for the Holy See. I pray the Lord that its members remain ever thus, continuing their tradition of seriousness and religious asceticism evangelical poverty, faithful observance of the Rule and Constitutions, renewing themselves in vigorous living and deep interior spirit—always ready, at the least gesture from Your Holiness, to go forward at once to assist the Church in her needs.

I know that Your heart suffers much these days on account of the happenings in the Church: for peace in the world, for the great needs of its peoples; but above all, for the lack of obedience of some, even Catholics, to the lofty teachings which You, assisted by the Holy Spirit and in the name of God, have given us. I offer Your Holiness my daily prayers and sufferings, the insignificant but sincere offering of the least of your sons, asking the Lord to comfort you with His grace to continue along the direct yet often burdensome way—in defense of those eternal truths which can never change with the times.

In the name of my spiritual sons and of the "Praying Groups" I thank Your Holiness for the clear and decisive words You have spoken in the recent encyclical, "Humanae Vitae", and I reaffirm my own faith and my unconditional obedience to Your inspired directives.

May God grant truth to triumph, and, may pence be given to His Church, tranquility to the people of the earth, and health and prosperity to Your Holiness, so that when these disturbing clouds pass over, the Reign of God may triumph in all hearts, through the Apostolic Works of the Supreme Shepherd of all Christians.

Prostrate at Your feet, I beg you to bless me, my Brothers in religion, my spiritual sons, the "Praying Groups", all the sick—that we may faithfully fulfill the good works done in the Name of Jesus and under your protection.

Your Holiness' most humble servant,

PADRE PIO, Capuchin
Taken from:
L'Osservatore Romano  1968  L'Osservatore Romano is the newspaper of the Holy See.