This feast originally instituted by Innocent XI in memory of the great victory won over the Turks before the walls of Vienna (September 13, 1683), was fixed for this date under Pope Pius X. Innocent XII had ordered that it should be kept on the Sunday within the Octave of the Nativity of Our Lady.
Whatever interpretation of the name of Mary we may accept, whether it means bitterness, the lady of the sea, or beloved of God, it is still the name of our Mother in heaven, the name which was first on the lips of the divine Child, the name which after that of Jesus holds all our hope of salvation. Many saints, especially St. Bernard and St. Gabriele dell’Addolorata, recognize in the most sweet name of Mary the virtues and prerogatives which the Doctors of the Church find in the name of the Savior, such as light, strength, sweetness, and protection. Therefore the devout Christian desires above all things to pronounce the holy name of Jesus and Mary with his last breath before going forth to behold their countenances.
St. Pius X granted great indulgences to those who should make use of this pious invocation.
(Source: The New Roman Missal, Rev. F. X. Lasance)