Halley wrote of this Comet in 1686: “In the summer of the year 1456 a Comet was seen, which passed in a retrograde direction between the earth and the sun. From its period and path, I infer that it was the same Comet as that of the years 1531, 1607 and 1682. I may therefore with confidence predict its return in the year 1758.” The appearance of the Comet in 1456 was so well remembered even 225 years later, because this was the scimitar-shaped Comet hailed by the conquering Turks as their guiding star, against the evil influence of which Pope Calixtus III. exhorted all Christians to pray to God. This story has been denied by certain latter-day sceptics, but the medieval historian Platina, who was living in Rome at the time, and who knew whereof he spoke, wrote in his “Lives of the Popes” in 1470: “A hairy and fiery star having then made its appearance for several days, the mathematicians declared that there would follow grievous pestilence, dearth and some great calamity. Calixtus, to avert the wrath of God, ordered supplications that if evils were impending for the human race He would turn all upon the Turks, the enemies of the Christian name. He likewise ordered, to move God by continual entreaty, that notice should be given by the bells to call the faithful at midday to aid by their prayers those engaged in battle with the Turk.” In truth, all Christendom appeared indeed to have fallen under the “wrath of God,” for the Turks; having wrested Constantinople away from the Christians, now came ravaging up the Danube countries and laid siege to the Christian city of Belgrade. Bloody battles were fought between the Magyars and Turks on the Danube, until Hunyadi, the great Magyar leader, at last overthrew the Turks under Mahomet II., under the walls of Belgrade, in a great battle, in which no less than 24,000 Turks were slain. This was on July 21st, on the eve of which day the Comet had been seen to blaze at its fiercest. 1378 The Comet appeared late in the year, and was seen at its brightest over Northern Europe, in Scotland, Scandinavia, Russia and Poland. All these countries, during the same period and immediately afterwards, were cursed by the terrible pestilence called the “Black Death,” now known to have been the worst visitation of the bubonic plague known in history. Wherever the dread sickness appeared, the people “died like rats.” So many succumbed to the disease, and so many others fled aghast from the pestilence, that whole cities and towns were left empty, and no labourers could be found to till the fields. 1301