Battle of Kōan

Battle of Kōan
Part of the Mongol invasions of Japan

Japanese attack ships. Mōko Shūrai Ekotoba (蒙古襲来絵詞), circa 1293.
DateAugust 15, 1281
LocationHakata Bay, near present-day Fukuoka, Kyūshū
Result Decisive Japanese victory. Invasion repulsed. Destruction of several vessels of the Mongol fleet.
Kamakura Japan

Mongol Empire

Commanders and leaders
Hōjō Sanemasa
Shōni Tsunesuke
Ōtomo Yoriyasu
Adachi Morimune
Kōno Michiari
Kikuchi Takefusa
Takezaki Suenaga
Hong Dagu
Kim Bang-gyeong
Fan Wenhu
~40,000-60,000 ~142,000 men in 4,400 ships
Casualties and losses
Unknown 120,000+

The Battle of Kōan (弘安の役 Kōan no eki), also known as the Second Battle of Hakata Bay, was the second attempt by the Mongol-founded Yuan Dynasty 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 sunk a sizeable portion of the Mongolian fleets. The invaders who reached the shore were repulsed shortly after landing. The Japanese called the opportune storm kamikaze ("divine wind"), a name that was used in the Second World War for pilots who carried out aerial suicide attacks.


After the failed first invasion by the Yuan navy, the Japanese made many defense preparations, constructing numerous fortifications along the coast. Armies of samurai trained in swordsmanship were kept in a state of readiness to repel a further attack.

In early 1280 Kublai Khan planned another invasion of Japan and ordered his shipbuilders to rebuild the whole fleet within a year. In the short time available many of the ships were poorly made; many were flat-bottomed river boats requisitioned by the Emperor.


By June 1281, 900 Yuan ships were gathered in Korea; the force was called the Eastern Route Army. They were crewed by 17,000 sailors, and transported 10,000 Korean soldiers and 15,000 Mongols and Chinese. The Southern Route Army, meanwhile, was assembled just south of the Yangtze River, in China. It is said to have consisted of 100,000 men on 3,500 ships. As before, Iki and Tsushima islands fell quickly to the much larger Yuan forces.

The Eastern Route Army arrived at Hakata Bay on June 21, and decided to proceed with the invasion without waiting for the larger Southern force which had still not left China. They were a short distance to the north and east of where their force had landed in 1274, and were in fact beyond the walls and defenses constructed by the Japanese. The samurai responded quickly, assaulting the invaders with waves of defenders, denying them the beachhead.

At night small boats carried small bands of samurai into the Yuan fleet in the bay. Under cover of darkness they boarded enemy ships, killed as many as they could, and withdrew before dawn. This harassing tactic led the Yuan forces to retreat to Tsushima, where they would wait for the Southern Route Army. However, over the course of the next several weeks, 3,000 men were killed in close quarters combat in the hot weather. Yuan forces never gained a beachhead.

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 percent 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".[1]


Kublai Khan began to gather forces to prepare for a third invasion attempt in 1284, but was soon distracted by events in Southeast and Central Asia, and no third attempt was ever made.



  1. Winters, pp. 14–15

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