In the pre-1970 calendar, September 24 was the feast of Our Lady of Ransom (also known as Our Lady of Mercy). It commemorated the apparitions of the Blessed Virgin Mary, on August 1, 1218, to St. Peter Nolasco, to his confessor Saint Raymond of Pennafort, and to King James I of Aragon. In response to this, Saint Peter Nolasco founded the Order of Our Lady of Mercy (Mercedarians), devoted to the redemption of Christians who had become Muslim captives. As Diarmaid Mac Culloch has noted in his monumental The Reformation: A History (2005), European Christians were still being captured and enslaved by Ottoman pirates in significant numbers well into the 16th century - a problem ultimately resolved only by the Turks' decisive naval defeat at Lepanto in 1571 and the ensuing decline of Ottoman power.
That decline ended the threat and therefore the significance (so it was alleged) of Our Lady of Ransom in the liturgical calendar. According to Cardinal Antonelli's account, on November 27, 1953, Pius XII's Pontifical Commission for the Reform of the Sacred Liturgy discussed the fate of this feast. Both Monsignor Enrico Dante and Father Augustine Bea, among others, favored its abolition - on the obvious grounds that the original object of the feast and of the Order no longer had the importance they once had had. Our Lady of Ransom survived the rubrical reform of 1960, but was reduced to a commemoration - before being dropped altogether in the more radical1969 calendar revision.
History may not literally repeat itself, but, with today's latest beheading of a French national by Islamic militants in Algeria, it seems evident that there has arisen again an acute danger to Westerners of capture by modern-day Islamists. So perhaps the liturgical reformers - in this (as in so many other matters relating to the calendar) - tragically misread the direction of history! In any case, the commemoration of Our Lady of Ransom shares with some other abandoned practices (like, for example, the Leonine prayer "for the freedom and exaltation of Holy Mother the Church") a renewed relevance in today's world of war, terrorism, and religious persecution.
Here (in the translation provided by my childhood Saint Joseph Daily MIssal) is the old Collect for the feast of Our Lady of Ransom: O God, by means of the most glorious Mother of Your Son, You were pleased to give new offspring to Your Church fro the ransoming of Christians from the power of the pagans; grant, we beseech You, that we too, who love and honor her as the foundress of so great a work, may by her merits and prayers be ourselves delivered from all our sins and from the bondage of the devil.