The Blue Army of Our Lady of Fátima, now mostly known as the World Apostolate of Fátima, is a public international association of the Christian faithful that has as its general purpose "the promotion of the authentic teaching of the Roman Catholic Church and the strict adherence to the tenets of the Gospel; the personal sanctification of adherents through faithful adherence to the Message of Fátima and the promotion of the common good by the spreading of that Message of Fátima".
The Blue Army was founded in 1946 by Rev. Fr. Harold V. Colgan, parish priest of St. Mary of Plainfield, New Jersey (USA). Father Colgan had fallen seriously ill and was hospitalized. During his illness he prayed to Our Lady of Fátima that if she should cure him he would spend the rest of his life spreading devotion to her. He attributed his recovery to his prayers and began preaching to his congregation on a regular basis about the Virgin Mary.
He summed up the message of Our Lady's apparition as this:
His message was highly successful; however, he wanted to make more of a lasting impression upon his congregation, and so he added two further items of his own invention. The first was a signed promise that one would try to uphold these values and the second was to wear a blue ribbon or blue medal in order to remember the promise. This was also a success and the congregation all enrolled. It was then that Fr. Colgan began to think about extending this to other parishes and other nations. Thus was born the Blue Army, from Colgan's own words: "We will be the Blue army of Mary and Christ, against the red of the world and of Satan."
Fr. Colgan began preaching his message and gained success, especially with the assistance of writer John Haffert who began delivering conferences on the message of Fátima and the Blue Army. Colgan then went to the Vatican in May 1947 to meet Pius XII in order to present his project for approval from the Pontiff. The foundation of the International Blue Army took place at the House of Pontevedra, Spain, where Mary is said to have appeared to request Communion of Reparation every First Saturday. Currently, there are over 20 million members.