J.M.J. "After the letters of Mother Mary of the Divine Heart (1863-1899) requesting, in the name of Christ Himself, that Pope Leo XIII to consecrate the world to the Sacred Heart of Jesus, the Holy Father commissions a group of theologians to examine the petition on the basis of revelation and sacred tradition. This investigation was positive. And so in the encyclical letter Annum Sacrum (May 25, 1899 A. D.) this same pope decreed that the consecration of the entire human race to the Sacred Heart of Jesus should take place on June 11, 1899 A. D. Later Pope Leo XIII encouraged the entire Roman Catholic episcopate to promote the devotion of the Nine First Fridays and he established June as the Month of the Sacred Heart. Pope St. Pius X decreed that the consecration of the human race, performed by Pope Leo XIII be renewed each year. Pope Pius XI in his encyclical letter Miserentissimus (May 8, 1928 A. D.) reaffirmed the importance of consecration and reparation to the Sacred Heart of Jesus. Finally Venerable Pope Pius XII, on the occasion of the 100th anniversary of Pope Pius IX's institution of the Feast, instructed the entire Catholic Church at length on the devotion to the Sacred Heart in his encyclical letter Haurietis aquas (May 15, 1956 A. D.)
"It was Venerable Pope Pius XII who first consecrated the Church and the world to the Immaculate Heart of Mary on October 31 and again, solemnly on December 8, 1942 A. D. In recent times, moved by millions of petitions and by the occasion of the attempted assassination of his own person on the Feast of Our Lady of Fatima, May 13, 1981, Pope John Paul II consecrated the world and every nation to the Immaculate Heart in 1982, and repeated this act in union with all the Catholic Bishops again in 1983 A.D."
--The Apostolate Alliance of the Two Hearts & Immaculate Mediatrix