21 Meanwhile, trusting in the protection of Mary the Virgin Immaculate, who not long ago We directed should be universally invoked as "Queen of Peace," as also in the intercession of the three Blessed to whom we have decreed the honour of saints, We humbly implore the Holy Ghost the Paraclete that He may "graciously grant to the Church the gifts of unity and peace", and may renew the face of the earth by a fresh outpouring of His charity for the salvation of all. As an earnest of these heavenly gifts and as a pledge of Our paternal benevolence, We impart with all Our heart to you, Venerable Brethren, to all your clergy and people, the Apostolic Benediction. Given at St. Peter's, Rome, on May 23, the Feast of Pentecost, 1920, and in the sixth year of Our Pontificate.
Source: Pacem, Dei Munus Pulcherrimum (Vatican.va)