Early in World War 1, Pope Benedict XV asked that the invocation “Queen of Peace” be added to the Litany of the Blessed Virgin Mary. At a Consistory of Cardinals on 24 December 1915 he said:

“When man has hardened his heart and hate has overrun the earth, when fire and sword convulse the world and make it resound with clash of arms and of wailing, when human plans have proved misleading, and when all social well-being is upset, faith and history point to Mary as the only refuge, the all-powerful intercessor, the Mediatrix of all grace… therefore, let us say with sure trust: Queen of Peace, pray for us!”

In a letter dated 5 May 1917, the Pope wrote to all the Bishops of the world formally asking that the invocation Queen of Peace, pray for us be added to the Litany of Loreto:

“…since all the graces which God deigns to bestow in pity upon men are dispensed through the most holy Virgin, We urge that more than ever in this terrible hour, the trusting petitions of her most afflicted children be directed to the august Mother of God….

“From every corner of the earth—from the majestic churches and the humble chapels; from the mansions of the rich as well as from the huts of the poor; from wherever dwells a faithful soul; from the bloodstained battlefields and war-swept seas, may this pious and ardent invocation arise to Mary, the Mother of Mercy who is all-powerful in grace! … May her loving and most merciful solicitude be moved to obtain for this convulsed world the peace so greatly desired!

“And may the ages yet to come remember the efficacy of Mary’s intercession and the greatness of her blessings to her suppliants!”

Eight days after the signing of this letter by Pope Benedict XV, Our Lady appeared for the first time to the young shepherds at Fatima.