Sapping and mining were now resorted to, and movable towers that could be pushed against the walls were provided, having grappling irons and drawbridges to let down upon the battlements, across which the fierce Janizaries could rush in hand to hand encounter with the defenders on or behind the ramparts. The hope and heart of Constantine were cheered at last by the sight of an approaching squadron of fourteen sail--among them five stout and lofty ships guided by skillful pilots and manned by the veterans of Italy and Greece long practiced in the arts and perils of the sea. The Emperor however fearing to open the harbor of the Golden Horn to the fleet of Mohammed, kept his own ships safely anchored behind the chains that protected the harbor and left these ships to fight out the battle alone. The ramparts, the camp, the coasts of Asia and Europe were lined with multitudes of spectators as these ships with joyful shouts sailed down upon the hostile fleet of three hundred vessels. Most of these however were huge boats crowded with troops but without artillery. Those who have in their eye the situation of city, harbor and shore, can easily conceive the scene and admire the grandeur of the spectacle. On came the ships in proud defiance. Their artillery swept the waters. Bullets, rocks and Greek fire were showered from these floating fortresses upon the huge flat galleys of the Turks. The weight of the Venetian vessels crushed them like seashells beneath their planks. Wielding their helms and sails as skillfully as the Turks did their horses, they spread death, disorder and flight among the hostile fleet and strewed the two beaches of Asia and Europe with their wrecks that burned as they drifted to the shore. In vain Mohammed spurred his horse breast deep into the sea and drew his scimitar against the Venetian vessels which were fighting but a few yards from him in the mouth of the Bosphorus. For a moment his cries and his presence encouraged his galleys but they were shattered anew. The Greeks struck down the iron chains that protected the harbor of the Golden Horn and the Christian ships entered it under full sail amid the shouts of soldiers and populace thronging the walls of the city. Twelve thousand Turks perished in this sea fight. The introduction of these supplies revived the hopes of the Greeks. The city could easily be saved by the sea. A rational and moderate armament of the maritime states might have saved the relics of the Roman name and maintained a Christian fortress in the heart of the Ottoman Empire. Yet this was the sole and feeble attempt to save Constantinople.