It was the year 1917, and Europe was living through the dark days of the First World War. Millions of people were dying on the battlefields, and in almost every house there was a family missing someone. The whole world seemed covered in shadow. But in Portugal, in a small, poor village called Fatima, something extraordinary was about to happen — something that would change the world.

Fatima was a humble place, with simple stone houses, dry fields, and very few trees. The families lived by keeping sheep and planting whatever the land would give. Three children lived there and looked after the flock: Lucia dos Santos, who was ten, and her cousins Francisco and Jacinta Marto, nine and seven years old. They did not know it yet, but they were about to become witnesses to the greatest Marian event of the twentieth century.

In 1916, one year before the great apparitions, something unusual happened. The three children were watching the sheep when they saw a very clear light coming toward them. Out of the light came the figure of a young man who seemed to be made of brightness.

"Do not be afraid," he said. "I am the Angel of Peace."

The children stood frozen with wonder, unable to say a word. The angel then taught them a prayer: "My God, I believe, I adore, I hope, and I love You." He appeared three times that year, preparing the children for something greater that was still to come. On his last visit, he gave them Holy Communion and asked them to offer prayers and sacrifices to the Most High.

The children told no one. They kept it in their hearts, like a secret. But something changed in them: they became quieter, more serious, more given to prayer. They were being prepared.

Then came the year 1917. It was the thirteenth of May, a Sunday. Lucia, Francisco, and Jacinta were at the Cova da Iria, a little valley among the hills where they usually pastured the sheep. It was midday, and the sky was clear and blue. Suddenly, they saw a flash of lightning.

"Thunder!" cried Jacinta. "Let's go home before the rain comes."

But there was not a single cloud in the sky. How strange. They started down the slope with the sheep when a second flash lit up the air. And then something happened that they would never forget.

Over a small holm oak, a low tree with tiny leaves, there hung a very bright light. And inside the light stood a Lady. She was the most beautiful woman the children had ever seen. She was dressed all in white, and her face shone like the sun — but it was a gentle brightness, one that did not hurt their eyes. She held a white rosary in her hands, and her gaze was sweet and sad at the same time. The three children were so amazed they could not move.

The Lady smiled tenderly and spoke:

"Do not be afraid. I will not harm you."

Lucia, who was the oldest, gathered her courage and asked, still trembling:

"Where do you come from, my Lady?"

"I come from Heaven," she answered.

"And what do you want of me?"

The answer was surprising:

"I have come to ask you to come here for six months in a row, on the thirteenth day, at this same hour. Then I will tell you who I am and what I want. And I will return here a seventh time."

The children could hardly believe what they were hearing. The Lady from Heaven wanted to see them again.

Then the Lady asked them a very serious question:

"Are you willing to offer yourselves to God, to bear all the sufferings He may wish to send you, in reparation for the sins by which He is offended, and in supplication for the conversion of sinners?"

"Yes, we are," Lucia answered for them all.

"Then you will have much to suffer," said the Lady kindly. "But the grace of God will be your comfort."

As she spoke these words, the Lady opened her hands, and from them came an immense light that entered the hearts of the three children. They felt as though they were plunged into God, wrapped in a love so great they could not explain it. Without saying anything to one another, they fell to their knees and repeated softly: "Most Holy Trinity, I adore You."

Before leaving, the Lady made one more request:

"Pray the Rosary every day, to obtain peace for the world and the end of the war."

Then she began to rise slowly, moving toward the east, until the light around her disappeared into the sky. The children stood in silence for a long time, unable to speak or move.

It was Lucia who whispered first:

"She was so beautiful..."

Jacinta was crying with joy:

"Oh, Lucia, Our Lady is so beautiful! So beautiful!"

And Francisco, who could see the Lady but could not hear her voice, kept asking:

"What did she say? What did she say?"

The children walked home changed. On the way, Lucia asked her cousins:

"Let's not tell anyone. It's our secret."

But Jacinta, at seven years old, had a heart so full that she could not keep it in. The moment she got home, she told her mother everything: they had seen a Lady from Heaven at the Cova da Iria, all white and shining, and she was going to come back. Her mother did not believe her. She thought it was the fancy of a child who spends all day in the fields. Soon, though, the whole village knew the story, and many people laughed at the children and mocked them.

Lucia's mother, Maria Rosa, was very angry. She was sure her daughter was lying and shaming the family, and she even punished her to make her take it all back. Lucia cried, but she always repeated the same thing: it was true, she had seen Our Lady. The parish priest had his doubts too, and warned that it might even be a trick of the devil.

But the children knew what they had seen, and nothing in the world could make them deny it. Francisco and Jacinta's parents, for their part, watched their children quietly. They saw that they were changed, more serious, more given to prayer, and they began to think that perhaps it was true.

Meanwhile, the children waited with pounding hearts for the thirteenth of June. They made sacrifices, as the Lady had asked: they gave their lunch to the poor and went hungry, and they went without water on hot days.

"We do it for sinners," Jacinta would explain.

Francisco spent long, quiet hours in the church, keeping Jesus company in the tabernacle, because he wanted to console him. Lucia prayed the Rosary while she watched the sheep. All three had been transformed by their meeting with Heaven.

At last the thirteenth of June arrived. About fifty curious people went with the children to the Cova da Iria, to see whether anything would really happen. At midday, the three saw the flash again, and Our Lady appeared over the holm oak.

"She is there," said Jacinta, pointing.

The people looked and saw nothing. Or almost nothing: some noticed a small cloud resting on the tree, and others heard a soft humming, like bees. But the Lady herself — only the three children could see and hear her. Our Lady spoke with them again. She asked for more prayer, more sacrifices, and said something mysterious about the Hearts of Jesus and Mary.

On the thirteenth of July came the third apparition, and this time about five thousand people arrived, because the news had spread through the whole region. Our Lady appeared once more and entrusted the children with something grave and important: the secret of Fatima, in three parts.

In the first part, the children were shown a vision of hell and saw the suffering of souls who turn away from God. It was so frightening that Jacinta was shaken for days afterward, crying.

"Lucia," she would say, "so many souls are lost. We must pray and make sacrifices for them."

The other parts of the secret spoke of the future: wars, persecutions, and suffering, but also the promise that, in the end, the Immaculate Heart of Mary would triumph. And Our Lady announced that in October she would work a great miracle, so that everyone could believe.

But not everyone was pleased about the apparitions. The government of Portugal in those days was against the Church. The administrator of the district of Ourem, a man named Artur Santos, did not believe in God and hated the whole story. On the thirteenth of August, he took the three children away by force and locked them in jail, in a cell with the prisoners. To pull the secret out of them, he even threatened to boil the three of them in a pot of oil.

The children were very afraid. They truly believed they were going to die. Even so, they told him nothing.

"You can kill us," said Lucia, her voice steady. "But the secret we will not tell."

Jacinta, seven years old, took a little medal of Our Lady from her pocket and began to pray the Rosary. The prisoners, moved by such a small girl, took off their hats and prayed along with her.

Defeated by that faith, the administrator finally let the children go. But because of the imprisonment, they could not be at the Cova da Iria on the thirteenth of August. Our Lady appeared to them a few days later, at a nearby place called Valinhos, and she was sad that they had not been able to come on the appointed day.

On the thirteenth of September, there were already some thirty thousand people at the Cova da Iria. This time, many of them saw strange things: the sun grew pale, so that they could look at it without hurting their eyes; a kind of rain of white petals fell from above and vanished before touching the ground; a soft light covered everything.

"A miracle!" the people cried. "It's a miracle."

But Our Lady repeated her promise to the children: the true miracle would come in October.

"In October I will perform a miracle, so that everyone may believe."

The stage was set for the most extraordinary event of Fatima.