On July 13, 1917, Our Lady appeared to Lucia, one of the visionaries of Fatima (Portugal), and to her two young cousins, while a crowd of 4,000 to 5,000 people had gathered at the site. The Virgin told the children: "I want you to come here on the 13th of next month. Continue to pray the Rosary every day in honor of Our Lady of the Rosary, to obtain peace in the world and the end of the war, because only she will be able to help you."
"May I ask you to tell us who you are," Lucia asked, "and to perform a miracle so that everyone will believe that Your Grace is appearing to us?"
"Continue coming here every month. In October, I will tell you who I am, what I want, and I will perform a miracle that everyone will be able to see, to help them believe. Sacrifice yourself for sinners, and often say to Jesus, especially when you make a sacrifice: ‘O Jesus, it is out of love for you, for the conversion of sinners, and in reparation for the sins committed against the Immaculate Heart of Mary’."
Saying these words, the Blessed Virgin opened her hands. The rays of light emanating from them seemed to penetrate the earth. The children then saw as it were a sea of fire, in which the demons and the souls of the damned were plunged. They were like transparent burning embers, all blackened or burnished bronze, in human form. They floated about in this ocean of smoke. The shrieks and groans of pain and despair were horrifyingly frightening... Afraid, and as if to ask for help, the children looked up at Our Lady.
Memoirs of Sister Lucia, Fatima 1991 (4th Memoir)
Marie de Nazareth