Between May and October of 1917, three shepherd children, Lucia and her cousins, Jacinta and Francisco reported visions of the Virgin Mary in the Cova da Iria fields outside the hamlet of Aljustrel.
They had this experience on the 13th day of each month at approximately the same hour. Lúcia described seeing Mary as "brighter than the sun, shedding rays of light clearer and stronger than a crystal glass filled with the most sparkling water and pierced by the burning rays of the sun".

According to Lúcia's account Mary confided to the children three secrets, known as the Three Secrets of Fatima. She exhorted the children to do penance and to make sacrifices to save sinners. The children wore tight cords around their waists to cause pain, abstained from drinking water on hot days, and performed other works of penance. Most important, Lúcia said Mary asked them to say the Rosary every day, reiterating many times that the Rosary was the key to personal and world peace.

The 3 secrets :

The first secret:

A vision of Hell, which Lucia describes in her Third Memoir, written in 1942, as follows:
"Our Lady showed us a great sea of fire which seemed to be under the earth. Plunged in this fire were demons and souls in human form, like transparent burning embers, all blackened or burnished bronze, floating about in the conflagration, now raised into the air by the flames that issued from within themselves together with great clouds of smoke, now falling back on every side like sparks in a huge fire, without weight or equilibrium, and amid shrieks and groans of pain and despair, which horrified us and made us tremble with fear. The demons could be distinguished by their terrifying and repulsive likeness to frightful and unknown animals, all black and transparent. This vision lasted but an instant. How can we ever be grateful enough to our kind heavenly Mother, who had already prepared us by promising, in the first Apparition, to take us to heaven. Otherwise, I think we would have died of fear and terror.".”

The second secret :

Included Mary's instructions on how to save souls from Hell and convert the world to the Catholic faith:
"You have seen hell where the souls of poor sinners go. To save them, God wishes to establish in the world devotion to my Immaculate Heart. If what I say to you is done, many souls will be saved and there will be peace. The war is going to end: but if people do not cease offending God, a worse one will break out during the Pontificate of Pius XI. When you see a night illuminated by an unknown light, know that this is the great sign given to you by God that he is about to punish the world for its crimes, by means of war, famine, and persecutions of the Church and of the Holy Father. To prevent this, I shall come to ask for the consecration of Russia to my Immaculate Heart, and the Communion of reparation on the First Saturdays. If my requests are heeded, Russia will be converted, and there will be peace; if not, she will spread her errors throughout the world, causing wars and persecutions of the Church. The good will be martyred; the Holy Father will have much to suffer; various nations will be annihilated. In the end, my Immaculate Heart will triumph. The Holy Father will consecrate Russia to me, and she shall be converted, and a period of peace will be granted to the world."

Lúcia reportedly saw Mary in private visions periodically throughout her life. Most significant was the apparition in Rianjo, Galicia in 1931, in which Sister Lúcia said that Jesus visited her, taught her two prayers, and delivered a message to give to the hierarchy of the Church.

In 1947, Sister Lúcia left the Dorothean order and joined the Carmelite order in a convent in Coimbra.

Lúcia died on February 13, 2000, at the age of 97.
Lúcia's cousins, the siblings Francisco and Jacinta were both victims of the Great Spanish Flu of 1919.

During the second apparition on June 13, 1917, the Virgin Mary predicted the deaths of two of the children, although Lucia did not tell anybody about these predictions until 1941. Some accounts, including the testimony of Olimpia Marto (mother of the two younger children) state that her children did not keep this information secret and ecstatically predicted their own deaths many times to her and to curious pilgrims. According to the 1941 account, on June 13, Lúcia asked the Virgin if the three children would go to heaven when they died. She heard Mary reply, "Yes, I shall take Francisco and Jacinta soon, but you will remain a little longer, since Jesus wishes you to make me known and loved on earth. He wishes also for you to establish devotion in the world to my Immaculate Heart.
Jacinta, in fact, accurately foretold the time and detailed circumstances of her death, according to Lúcia and hospital staff.

Exhumed in 1935 and again in 1951, Jacinta's body was found incorrupt. Francisco’s had decomposed.

The Third Secret:

The third part of the secret was written down "by order of His Excellency the Bishop of Leiria and the Most Holy Mother ..." on 3rd January 1944. Bishop da Silva, visiting Lucia on 15th September 1943 while she was bed-ridden, first suggested that she write the third secret down to ensure that it would be recorded in the event of her death. Lucia was hesitant to do so.

Finally, in mid-October, Bishop da Silva sent her a letter containing a direct order to record the secret, and Lucia obeyed. In June of 1944, the sealed envelope containing the third secret was delivered to da Silva, where it stayed until 1957, when it was finally delivered to Rome.
It was announced on 13th May 2000, 83 years after the first apparition of the Lady to the children in the Cova da Iria, that the third secret would finally be released. The text was published on 26th June 2000:

The third part of the secret revealed at the Cova da Iria-Fatima, on 13 July 1917.
I write in obedience to you, my God, who command me to do so through his Excellency the Bishop of Leiria and through your Most Holy Mother and mine.
After the two parts which I have already explained, at the left of Our Lady and a little above, we saw an Angel with a flaming sword in his left hand; flashing, it gave out flames that looked as though they would set the world on fire; but they died out in contact with the splendour that Our Lady radiated towards him from her right hand: pointing to the earth with his right hand, the Angel cried out in a loud voice: 'Penance, Penance, Penance!'. And we saw in an immense light that is God: ‘something similar to how people appear in a mirror when they pass in front of it' a Bishop dressed in White 'we had the impression that it was the Holy Father'. Other Bishops, Priests, men and women Religious going up a steep mountain, at the top of which there was a big Cross of rough-hewn trunks as of a cork-tree with the bark; before reaching there the Holy Father passed through a big city half in ruins and half trembling with halting step, afflicted with pain and sorrow, he prayed for the souls of the corpses he met on his way; having reached the top of the mountain, on his knees at the foot of the big Cross he was killed by a group of soldiers who fired bullets and arrows at him, and in the same way there died one after another the other Bishops, Priests, men and women Religious, and various lay people of different ranks and positions. Beneath the two arms of the Cross there were two Angels each with a crystal aspersorium in his hand, in which they gathered up the blood of the Martyrs and with it sprinkled the souls that were making their way to God.

Controversies of Fatima

Fatima is not without controversy. The apparitions occurred during a period when Freemasons had gained influence in Portugal and attempted to limit the power of the Catholic Church following the republican revolution of October 5, 1910.

Many Catholics felt persecuted, leading to a polarization of Portuguese society between the largely urban liberals and the largely rural and more conservative Catholics. Secularists may have viewed the apparitions as an attempt by the Church to reassert political control. The detention of the children by the provincial administrator reflects this concern.

Following the rise of the counter-revolutionaries in the military revolution of 1926, devotion to Our Lady of Fatima became encouraged.

In 1992 details relating to the apparitions, which had previously been unreleased, were finally revealed. A priest who had interviewed the children at the time of the apparitions reported their description of the Lady wearing a short skirt, earrings and a necklace with a medallion.

This did not accord with the norms expected of the Blessed Virgin and was not included in the official reports at the time.

In the Documentação Crítica de Fátima, Doc. 2, pp. 11–12 Cónego Formigão, who also participated in the inquiries, said:
"Jacinta declares that Our Lady's dress goes down only to her knees. Our Lady can only appear dressed, obviously, in the most decent and modest way. The dress would have to come down to her feet. Any other way constitutes the most serious obstacle to the supernaturalism of the apparition and makes us think that it is a mystification prepared by the Spirit of Darkness. But how can we explain the belief of so many thousands of people, their living faith and burning piety, the modesty and the composure they show in all their acts, the silence and behavior of the crowd, the numerous and astonishing conversions caused by the events, the appearance of extraordinary signs in the sky and on the earth, verified by thousands of witnesses? How can we explain, I repeat, all these facts and conciliate them with divine providence and the laws that rule the supernatural world, above all after the establishment of Christianity, if the Demon is the cause of such events? (Documentação, Doc. 7, pp. 66–67, cited in Armada and Fernandes, p. 190)
The earrings worn by the Virgin were assimilated into a "halo" of light around her head in the descriptions issued in the aftermath of the apparitions with no mention of the actual jewelery observed by the children.
The short dress worn by the Virgin during the apparitions did not form part of any official description released at the time, instead, and in sharp contrast, the Virgin was reported as saying: "Certain fashions will be introduced which will offend my Son (Jesus) very much."
In the 1940s, Pius XII was asked his opinion of what women teaching in Italian schools should wear to preserve their modesty. He replied "Below the knee, halfway down the arm, and two finger widths below the collarbone." which the Virgin is described as having breached during the Fatima apparitions.


Controversy Around Sister Lúcia

There have been accusations of a campaign to cover up the message of Fatima by ecclesiastical authorities within the Catholic Church, including the motivation behind imposing an order of silence against Sister Lucia. Lúcia was already under orders of silence as a Carmelite sister, giving no interviews or statements to the public without permission, and she continued to write private diaries and personal letters up until her death.
However, when journalists sought out Sister Lúcia after the Vatican refused to release the Third Secret in 1960, they found it had become increasingly difficult to see her. She was forbidden not only to reveal the Secret but also to speak about the Third Secret at all. She could not, from 1960 forward, receive any visitors except close relatives.
Even her confessor of many years, Father Aparicio, who had been in Brazil for over twenty years, was not permitted to see her when he visited Portugal. He stated: "I have not been able to speak with Sister Lúcia because the Archbishop could not give the permission to meet her. The conditions of isolation in which she finds herself have been imposed by the Holy See. Consequently, no one may speak with her without a license from Rome."
More than forty years later, Sister Lúcia remained under the imposition of silence. Only the Pope at the time could grant the permission necessary for her to speak openly or to be visited.

Sister Lúcia was forbidden to reveal the Fatima Secret. She remained under an order of silence until her death in February 2005, unable to speak freely about Fatima without special permission from the Vatican.