Pope Pius XII
Mystici Corporis Christi §112
Mystici Corporis Christi: On the Mystical Body of Christ
112 Confiding in this sublime hope, from an overflowing heart We impart to you, one and all, Venerable Brethren, and to the flocks entrusted to your care, as a pledge of heavenly graces and a token of Our special affection, the Apostolic Benediction. Given at Rome, at St. Peter's on the twenty-ninth day of June, the Feast of the Holy Apostles Peter and Paul, in the year 1943, the fifth of Our Pontificate.
Source: Mystici Corporis Christi (Vatican.va)