Battle of Kōan

The Battle of Kōan, also known as the Second Battle of Hakata Bay, was the second attempt by the Mongol-led Yuan dynasty of China to invade Japan after their failed attempt seven years earlier at the Battle of Bun'ei. In the summer of 1281, the Yuan invaded with two large armies. The Japanese defenders were aided by a major storm which sank a sizeable portion of the Yuan fleets. The invaders who reached the shore were repulsed shortly after landing. The Japanese called the opportune storm kamikaze (lit. 'divine wind'), a name later used in the Second World War for pilots who carried out aerial suicide attacks.

The first of the Southern force ships arrived on July 16, and by August 12 the two fleets were ready to attack Japan. On August 15 a major tempest struck the Tsushima Straits, lasting two full days and destroying most of the Yuan fleet. Contemporary Japanese accounts indicate that over 4,000 ships were destroyed in the storm; 80% of the Yuan soldiers either drowned or were killed by samurai on the beaches. The loss of ships was so great that "a person could walk across from one point of land to another on a mass of wreckage".