"Our Lady of Victory commonly celebrated as Our Lady of the Holy Rosary"

from Abbot Gueranger's "The Liturgical Year":

Soliman II, the greatest of the Sultans, taking advantage of the confusion caused in the west by Luther, had filled the sixteenth century with terror by his exploits. He left to his son, Selim II, the prospect of being able at length to carry out the ambition of his race: to subjugate Rome and Vienna, the Pope and the emperor, to the power of the crescent. The Turkish fleet had already mastered the greater part of the Mediterranean, and was threatening Italy, when, on October 7, 1571, it came into action, in the Gulf of Lepanto, with the pontifical galleys supported by the fleets of Spain and Venice. It was Sunday; throughout the world the confraternities of the rosary were engaged in their work of intercession. Supernaturally enlightened, St. Pius V watched from the Vatican the battle undertaken by the leader he had chosen, Don John of Austria, against the three hundred vessels of Islam. The illustrious Pontiff, whose life’s work was now completed, did not survive to celebrate the anniversary of the triumph; but he perpetuated the memory of it by an annual commemoration of our Lady of Victory. His successor, Gregory XIII, altered this title to our Lady of the rosary, and appointed the first Sunday of October for the new feast, authorizing its celebration in those churches which possessed an altar under that invocation.

A century and a half later, this limited concession was made general. As Innocent XI, in memory of the deliverance of Vienna [from the Mohammedans] by Sobieski, had extended the feast of the most holy name of Mary to the whole Church; so, in 1716, Clement XI inscribed the feast of the rosary on the universal calendar, in gratitude for the victory [over Islam] gained by Prince Eugene at Peterwardein, on August 5, under the auspices of our Lady of the snow. This victory was followed by the raising of the siege of Corfu and completed a year later by the taking of Belgrade.

Magnificat antiphon:

Beata Mater et intacta Virgo, gloriosa Regina mundi, sentiant omnes tuum juvamen quicumque celebrant tuam sanctissimi rosarii solemnitatem.

"Blessed Mother and unspotted Virgin, glorious Queen of the world, may all experience thine aid, who celebrate thy solemnity of the most holy rosary."