Upon hearing this, Khublai began the preparation of the mightiest of his invading hosts. To be braved by a little island nation, when his sceptre ruled from the Dnieper to the Yellow Sea, was not to be thought of. Various fleets and contingents sailed from different ports in China and made rendezvous on the Corean coast. The fleet was composed of 3,500 war junks, of large size, having on board 180,000 Chinese, Mongols, and Coreans. Among their engines of war were the catapults which the Polos had taught them to make. They set sail in the autumn of 1281. From the very first the enterprise miscarried. The general-in-chief fell sick and the command devolved on a subordinate, who had no plan of operation. The various divisions of the force became separated. It is probable that the majority of them never reached the mainland of Japan. The Mongol and Corean contingent reached the province of Chikuzen, but were not allowed to make a successful landing, for the Japanese drove them back with sword and fire. The Chinese division, arriving later, was met by a terrible tempest that nearly annihilated them and destroyed the ships already engaged. The broken remnant of the fleet and armies, taking refuge on the island of Iki, were attacked by the Japanese and nearly all slain, imprisoned, or beheaded in cold blood. Only a few reached Corea to tell the tale. The “Mongol civilization,” so-called, seems to have had little influence on Corea. The mighty empire of Genghis soon broke into many fragments. The vast fabric of his government melted like a sand house before an incoming wave, and that wave receding left scarcely a sediment recognizable on the polity or social life of Corea. Marco Polo in his book hardly mentions the country, though describing Zipangu or Japan quite fully. One evil effect of their forced assistance given to the Mongols, was that the hatred of the Japanese and Coreans for each other was mutually intensified. After the Mongolian invasion begins that series of piratical raids on their coast and robbery of their vessels at sea, by Japanese adventurers, that made navigation beyond sight of land and ship-building among the Coreans almost a lost art. The centuries following the Mongol invasion were periods of anarchy and civil war in Japan, and the central government authority being weak the pirates could not be controlled. Building or stealing ships, bands of Japanese sailors or ex-soldiers put to sea, capturing Corean boats, junks, and surf-rafts. Landing, they harried the shores and robbed and murdered the defenceless people. Growing bolder, the marauders sailed into the Yellow Sea and landed even in China and in Liao Tung. They kept whole towns and cities in terror, and a chain of coast forts had to be built in Shan-tung to defend that province.