Alan (French Alain) de la Roche was born around 1428 in Brittany to a Breton Catholic family. He entered the Dominican Order at Dinan and studied at the Dominican Convent of Saint-Jacques at Paris.
Alan became the principal Dominican Rosary-promoter of the late 15th century. Around 1470, at the Dominican convent of Douai, Alan received (per his reported private revelations) a revelation from the Blessed Virgin Mary — instructing him to restore and institutionally promote the Holy Rosary devotion.
The Holy Rosary — the Marian meditative-prayer devotion combining the recitation of the Ave Maria with the meditation on the mysteries of the Life of Christ and the Blessed Virgin — had been developing gradually through the medieval Catholic tradition (with earlier attributed Marian revelations to St. Dominic himself in the 13th century, the 15-decade meditative-Rosary structure elaborated in the 14th and 15th centuries).
Alan undertook the systematic institutional promotion of the Rosary — establishing the Rosary Confraternities across the Northern European Dominican provinces (France, Flanders, Germany, the Low Countries).
The first documented Rosary Confraternity was established by Alan at Douai in 1470; the Cologne Rosary Confraternity was established by Jakob Sprenger (the Dominican Inquisitor who co-authored the Malleus Maleficarum) in 1475 — establishing the Rosary Confraternity as the principal Catholic devotional-organizational structure that would extend through the late-medieval, early-modern, and modern Catholic Rosary tradition.
Alan composed multiple Rosary-devotional treatises and the 'Great Book of the Miracles of the Holy Rosary'. He died at Zwolle in the Low Countries on September 8, 1475 — the feast of the Birth of the Blessed Virgin.
The Rosary tradition established by Alan underpinned the institutional Rosary tradition of the Catholic Church: the 1571 attribution of the Battle of Lepanto Christian naval victory to the Rosary intercession by Pope St. Pius V, the foundation of the Feast of Our Lady of the Rosary (October 7) by Pope St. Pius V, the Marian apparitions centred on the Rosary (Fatima 1917), and the continuing Rosary devotion to the present day.