May 13th is indeed a significant day in the Catholic Church, as it commemorates the first apparition of the Blessed Virgin Mary to three shepherd children—Lucia Santos and her cousins, Francisco and Jacinta Marto—in Fatima, Portugal, in 1917.
According to the children's accounts, Mary appeared to them six times between May 13th and October 13th, 1917, delivering messages of peace, repentance, prayer, and devotion to her Immaculate Heart. The most famous of these apparitions occurred on October 13th, when the Miracle of the Sun was witnessed by thousands of people gathered at the site.
The messages of Fatima are deeply significant to Catholics, emphasizing the importance of prayer, penance, and devotion to Mary as a means of obtaining peace for the world. The Catholic Church officially recognizes the events at Fatima and has designated May 13th as the Feast of Our Lady of Fatima, a day to honor Mary's role in bringing these messages to humanity and to reflect on their continued relevance.
On this day, Catholics often participate in special Masses, processions, and prayers dedicated to Our Lady of Fatima, seeking her intercession for peace and for the fulfillment of her requests made at Fatima. These include praying the Rosary daily, making sacrifices for sinners, and practicing devotion to Mary's Immaculate Heart.