The history of the gate has an interest of its own. When the Emperor Frederick Barbarossa was at Philippopolis, on his way to the Holy Land at the head of the Third Crusade, the prevalent suspicion that he had designs upon the Byzantine Empire found expression in the prophecy of a certain Dositheos, a monk of the Monastery of St. John Studius, that the German emperor would capture Constantinople, and penetrate into the city through this entrance. Thereupon, with the view of averting the calamity and preventing the fulfilment of the prophecy, Isaac Angelus ordered the gate to be securely built up.[384] In 1346 the partisans of John Cantacuzene proposed to admit him into the city by breaking the gate open, after its long close.[385] But what gives to the Kerko Porta its chief renown is the part which, according to Ducas, it played in the catastrophe of 1453, under the following circumstances. A large portion of the Outer Wall, at the Mesoteichion, having been overthrown by the Turkish cannon, the besieged were unable to issue from the city to the peribolos without being exposed to the enemy’s fire. In this extremity some old men, who knew the fortifications well, informed the emperor of a secret postern long closed up and buried underground, at the lower part of the palace, by which communication with the peribolos might be established.[386] This was done, to the great advantage of the Greeks. But on the last day of the siege, while the enemy was attempting to scale the walls with ladders at several points, a band of fifty Turkish nobles detected the newly opened entrance, rushed in, and mounting the walls from the interior of the city, killed or drove off the defenders on the summit. Thus a portion of the fortifications was secured against which scaling-ladders could be applied without any difficulty, and soon a considerable Turkish force stood on the Inner Wall, planted their standards on the towers, and opened a rear fire upon the Greeks, who were fighting in the peribolos to prevent the Turks from entering at the great breach. The cry rose that the city was taken, whereupon an indescribable panic seized the Greeks, already disheartened by the loss of Giustiniani, and, abandoning all further resistance, they fled into the city through the Gate of Charisius, many being trampled to death in the rout. The emperor fell at his post; and the Turks poured into the city without opposition.[387] The fate of Constantinople was thus scaled by the opening of the Kerko Porta.