In his 1954 encyclical on Mary’s Queenship, Ad Caeli Reginam, Pope Pius XII wrote:
“From the earliest ages of the Catholic church a Christian people, whether in time of triumph or more especially in time of crisis, has addressed prayers of petition and hymns of praise and veneration to the Queen of Heaven. And never has that hope wavered which they placed in the Mother of the Divine King, Jesus Christ; nor has that faith ever failed by which we are taught that Mary, the Virgin Mother of God, reigns with a mother’s solicitude over the entire world, just as she is crowned in heavenly blessedness with the glory of a Queen.” (emphasis ours)
Pius XII explained the theological reasons for her title of “Queen” in a radio message on May 13, 1946:
“He, the Son of God, reflects on His heavenly Mother the glory, the majesty and the dominion of His kingship, for, having been associated to the King of Martyrs in the … work of human Redemption as Mother and cooperator, she remains forever associated to Him, with a practically unlimited power, in the distribution of the graces which flow from the Redemption. Jesus is King throughout all eternity by nature and by right of conquest: through Him, with Him, and subordinate to Him, Mary is Queen by grace, by divine relationship, by right of conquest, and by singular choice [of the Father].”
-Tonia Long, “The Story of the Queenship of Mary”
Read the full article: https://americaneedsfatima.org/articles/the-queenship-of-mary