Mongol invasions of Japan

The Mongol invasions of Japan were two seaborne attacks launched by Kublai Khan, ruler of the Mongol Yuan dynasty, in 1274 and 1281, after the Korean kingdom of Goryeo had become a Mongol vassal. Both failed, the second largely because a typhoon wrecked the invasion fleet. The campaigns marked one of the limits of Mongol expansion, became founding events in Japan's sense of itself, and gave the Japanese language the word kamikaze, "divine wind".

Kublai Khan became khagan in 1260 and, after decades of Mongol campaigns in Korea, had made Goryeo a vassal. Japan was governed in practice by the Hōjō family, who ruled as regents for the shoguns of the Kamakura shogunate; their leader at the time was Hōjō Tokimune. Between 1266 and 1273 Mongol and Korean envoys travelled to Japan six times with letters demanding submission. The Japanese ignored the demands, and the envoys went home without an answer. Expecting attack, the authorities began strengthening the defences of Kyushu.

In 1274 Goryeo was made to build several hundred ships. The invasion force, perhaps around 15,000 Mongol, Chinese and Jurchen soldiers, 6,000 to 8,000 Korean troops and some 7,000 Korean sailors, sailed from southern Korea in November. It overwhelmed the small garrisons on Tsushima and Iki, where the defending commanders Sō Sukekuni and Taira no Kagetaka were killed and many islanders massacred.

The fleet then landed in Hakata Bay on the coast of Kyushu. The size of the defending army is uncertain; the historian Thomas Conlan puts the forces engaged on each side at around 3,000, while Japanese historians suggest about 6,000 defenders. The samurai, unfamiliar with foreign tactics, were confronted by tightly packed infantry behind shields and by explosive bombs that frightened their horses. By nightfall the invaders had pushed the Japanese back from the shore, but one of their commanders had been badly wounded, and the generals decided to return to the ships for the night. By morning most of the fleet had gone. A storm wrecked many vessels on the way back, and it is said that of some 30,000 invaders, 13,500 did not return.

The shogunate expected the Mongols to come back. It organised the warriors of Kyushu, built forts, and in 1276 raised a stone wall about two metres high around Hakata Bay. When Kublai sent envoys again in 1275 and 1279, the Japanese beheaded them. By 1279 the Mongols had completed the conquest of the Song dynasty and could draw on the shipyards and manpower of southern China.

Two fleets set out in 1281, one from Korea and a larger one from southern China; Yuan records speak of about 4,400 ships and 142,000 men. Modern historians consider these figures exaggerated: Conlan suggests a force perhaps a tenth as large, while Morris Rossabi proposes around 70,000. The Korean fleet arrived first and attacked Tsushima and Iki, but it could not land at Hakata because of the wall, and Japanese warriors raided its anchored ships at night in small boats. After the southern fleet joined it, fighting around Hakata settled into a stalemate.

On 15 August a typhoon struck the fleet at anchor and destroyed much of it. According to surviving accounts, the Japanese killed the captured Mongols, Koreans and northern Chinese but spared the southern Chinese, who were enslaved. Korean sources record that 7,592 of 26,989 Koreans failed to return, and Chinese and Mongol sources suggest losses of 60 to 90 per cent.

The disaster cost the Mongols much of their naval strength and exhausted Korea's shipbuilding. In Japan, a defensive war brought no conquered land with which to reward the warriors who had fought, and the authority of the Kamakura shogunate suffered. The storms were seen as divine protection, a belief that fed the idea that Japan could not be successfully invaded; in World War II the word kamikaze was revived for pilots who deliberately crashed into enemy ships.

Our 1279 map shows Kublai's Yuan dynasty and Goryeo facing the Kamakura shogunate across the sea in Japan, between the two invasions.