Readers of Tolkien will recall that Sauron fell on March 25. In choosing that date, Tolkien acted as a good medievalist. The Feast of the Annunciation itself commemorates the revelation by an angel to the Virgin Mary that she had conceived Jesus: nine months from Christmas, you see. By rumor and tradition, however, almost everything important that ever happened was ascribed to March 25, if it could not be positively dated otherwise. As the Catholic Encyclopedia explains:
All Christian antiquity (against all astronomical possibility) recognized the 25th of March as the actual day of Our Lord's death. The opinion that the Incarnation also took place on that date is found in the pseudo-Cyprianic work "De Pascha Computus", c. 240. It argues that the coming of Our Lord and His death must have coincided with the creation and fall of Adam. And since the world was created in spring, the Saviour was also conceived and died shortly after the equinox of spring...Consequently the ancient martyrologies assign to the 25th of March the creation of Adam and the crucifixion of Our Lord; also, the fall of Lucifer, the passing of Israel through the Red Sea and the immolation of Isaac.
And if March 25 is the anniversary of the Creation, then it follows, sort of, that it is likely to be the date of the Second Coming. Dr. Richard Landes notes this document from about the year AD 1000:
Abbo, scholasticus, then abbot of Saint-Benoit of Fleury sur Loire (ca.945-1004) [wrote a letter to the king] of France dated ca. 994-996 [in which] Abbo recalls several incidents of apocalyptic rumors circulating in earlier years:
[M]y abbot of blessed memory and keen mind rejected another error which grew about the End of the World; and after he received correspondence from Lotharingians he ordered me to answer. For a rumor had filled almost the entire world that when the Annunciation fell on Good Friday, without any question, it would be the End of the World.