Battle of Kōan

Japanese attack ships. Mōko Shūrai Ekotoba (蒙古襲来絵詞), circa 1293.

Date	August 15, 1281
Location	Hakata Bay, near present-day Fukuoka, Kyūshū
Result	Decisive Japanese victory. Invasion repulsed. Destruction of several vessels of the Mongol fleet.

Belligerents

Kamakura Japan

Mongol Empire

Yuan Dynasty

Goryeo

Commanders and leaders

Hōjō Sanemasa ()
Shōni Tsunesuke ()
Ōtomo Yoriyasu ()
Adachi Morimune ()
Kōno Michiari ()
Kikuchi Takefusa
Takezaki Suenaga
Shimazu Nagahisa

Atagai ()
Hindun ()
Hong Dagu
Kim Bang-gyeong ()
Fan Wenhu ()

Strength

~40,000-60,000

~142,000 men in 4,400 ships

Casualties and losses

Unknown

120,000+

Mongol Empire

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 Mongolian 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.

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