Mongol Invasions of Japan - Second Invasion

Second Invasion

In the spring of 1281, the Mongols sent two separate forces. An impressive force of 900 ships containing 40,000 Korean, Chinese, and Mongol troops set out from Masan, while an even larger force of 100,000 sailed from southern China in 3,500 ships. The Mongols' plan called for an overwhelming coordinated attack from the combined imperial Yuan fleets. The Chinese fleet of the Yuan was delayed by difficulties in provisioning and manning the large number of ships they had. Their Korean fleet set sail, suffered heavy losses at Tsushima, and turned back. In the summer, the combined Korean/Chinese fleet took Iki-shima, and moved on to Kyūshū, landing at a number of separate positions. In a number of individual skirmishes, known collectively as the Battle of Kōan (弘安の役), or the "Second Battle of Hakata Bay", the Mongol forces were driven back to their ships. The Japanese army was heavily outnumbered, but had fortified the coastal line, and was easily able to repulse the auxiliaries that were launched against it. Beginning August 15, the now-famous kamikaze, a massive typhoon, assaulted the shores of Kyūshū for two days straight, and destroyed much of the Mongol fleet.

Furthermore, it is now believed that the destruction of the Mongol fleet was greatly facilitated by an additional factor. Most of the invasion force was composed of hastily-acquired flat-bottomed Chinese riverboats and ships built in Goryeo of a similar type. According to Goryeosa, Southern Song type ships were too costly and their construction was too slow, so the traditional types were constructed. Such ships (unlike ocean-going ships, which have a curved keel to prevent capsizing) were difficult to use on high seas, let alone during a massive typhoon.