It's the feast of Our Lady of the Rosary--formerly known as "Our Lady of Victory," in honor of the significant naval victory of European forces over the "Turks" at Lepanto in 1574 (I think that's the date!). From what I read about this, the victory itself was not significant militarily, but it was enormously significant from the standpoint of European morale, because up to that point, it seemed as if the Turkish forces were utterly unstoppable. They owned the seas, and they had designs on the land. The European victory proved that it was possible for the tide to turn, and by that very fact, Lepanto became a turning point in European history.
If I remember correctly from what I read about this, the European forces were every bit as brutal and bloodthirsty as their opponents, even using severed heads as cannon balls, so I refuse to speak of them as "Christian," even though they were baptized, and the armada was called together under Papal authority. There is room for repentance even in a victory attributed to Mary and the Rosary.