Mongol invasions of Japan

Background

After a series of Mongol invasions of Korea between 1231 and 1281, Goryeo signed a treaty in favor of the Mongols and became a vassal state. Kublai was declared Khagan of the Mongol Empire in 1260 (although this was not widely recognized by the Mongols in the west) and established his capital at Khanbaliq (within modern Beijing) in 1264.

Japan at the time was ruled by the Shikken or Shogunate Regents of the Hōjō clan, who had intermarried with and wrested control from Minamoto no Yoriie, shogun of the Kamakura shogunate, after his death in 1203. The inner circle of the Hōjō clan had become so preeminent that they no longer consulted the council of the shogunate (Hyōjō (評定)), the Imperial Court of Kyoto, or their gokenin vassals, and made their decisions at private meetings in their residences (yoriai (寄合)).

The Mongols also made attempts to subjugate the native peoples of Sakhalin—the Ainu, Orok, and Nivkh peoples—from 1260 to 1308.

Contact

In 1266, Kublai Khan dispatched emissaries to Japan with a letter saying:

Cherished by the Mandate of Heaven, the Great Mongol emperor sends this letter to the King of Japan. The sovereigns of small countries, sharing borders with each other, have for a long time been concerned to communicate with each other and become friendly. Especially since my ancestor governed at heaven's command, innumerable countries from afar disputed our power and slighted our virtue. Goryeo rendered thanks for my ceasefire and for restoring their land and people when I ascended the throne. Our relation is feudatory like a father and son. We think you already know this. Goryeo is my eastern tributary. Japan was allied with Goryeo and sometimes with China since the founding of your country; however, Japan has never dispatched ambassadors since my ascending the throne. We are afraid that the Kingdom is yet to know this. Hence we dispatched a mission with our letter particularly expressing our wishes. Enter into friendly relations with each other from now on. We think all countries belong to one family. How are we in the right, unless we comprehend this? Nobody would wish to resort to arms.

Kublai essentially demanded that Japan become a vassal and send tribute under a threat of conflict. However, the emissaries returned empty-handed. A second set of emissaries were sent in 1268, returning empty-handed like the first. Both sets of emissaries met with the Chinzei Bugyō, or Defense Commissioner for the West, who passed on the message to Shikken, Hōjō Tokimune, Japan's ruler in Kamakura and to the Emperor of Japan in Kyoto.

After discussing the letters with his inner circle, there was much debate, but the Shikken had his mind made up; he had the emissaries sent back with no answer. The Mongols continued to send demands, some through Korean emissaries and some through Mongol ambassadors on March 7, 1269; September 17, 1269; September 1271; and May 1272. However, each time, the bearers were not permitted to land in Kyushu.

The Imperial Court suggested compromise, but really had little effect in the matter, due to political marginalization after the Jōkyū War. The uncompromising shogunate ordered all those who held fiefs in Kyūshū, the area closest to the Korean Peninsula and thus most likely to be attacked, to return to their lands and forces in Kyūshū moved west, further securing the most likely landing points.

After acknowledging its importance, the Imperial Court led great prayer services, and much government business was put off to deal with this crisis.

First invasion preparations

The Khan was willing to go to war as early as 1268 after having been rebuffed twice, but found that his empire did not have the resources to provide him with a sufficient navy at that time. With Mongol entry into the Korean court by marriage of the Korean crown prince to Kublai Khan's daughter, a mass construction of ships began on Korea's south-eastern shores, while the Mongols continued to demand Japan's surrender.

Kublai Khan founded the Yuan dynasty in 1271. In 1272, King Chungnyeol offered counsel to Kublai Khan. According to Goryeosa, Japan is yet to know the world is hallowed. So dispatch emissaries and convey our military power to Japan. Battle ships and military rations are well prepared. If you appoint me, I encourage you to the extent of my power. According to the History of Yuan, King of Goryeo ask Kublai Khan for conquering Japan. I am building 150 ships and encourage your conquest of Japan.

First invasion (1274)

In 1274, the Yuan fleet set out with an estimated 15,000 Mongol and Chinese soldiers and 8000 Korean soldiers in 300 large vessels and 400-500 smaller craft, although figures vary considerably depending on the source. The primary port for the operation was Quanzhou in Fujian, then the center of China's maritime trade. They landed on Komodahama beach on Tsushima Island on October 5, 1274. Sō Sukekuni, governor of Tsushima, led a cavalry unit of 80 to defend the island, but he and his outnumbered unit were killed in the engagement.

The Mongols and Koreans subsequently invaded Iki. Tairano Takakage, the Governor of Iki, fought the invaders with about 100 of his cavalrymen, but he killed himself after his unit was defeated.

The Mongol forces landed on November 19 in Hakata Bay, a short distance from Dazaifu, the ancient administrative capital of Kyūshū. The following day brought the Battle of Bun'ei (文永の役), also known as the "First Battle of Hakata Bay".

The Japanese were inexperienced in managing such a large force (all of North Kyūshū had been mobilized), and the Mongols made significant initial progress. It had been approximately 50 years since the last major combat event in Japan (Go-Toba's adherents in 1221), leaving not a single Japanese general with adequate experience in moving large bodies of troops. In addition, the style of warfare that was customary within feudal Japan involved single combat, even on large battlefields.

The Mongols possessed foreign weapons which included superior long-range armaments (the short composite bows that the Mongols were famous for, with poisoned arrows, fire arrows, bow-launched arrows with small rocket engines attached and gunpowder-packed exploding arrows and grenades with ceramic shells thrown by slings to terrify the enemy's horses), and easily had the upper hand in open land combat. The Japanese force at Hakata Bay needed time to await the arrival of reinforcements, with which they would be able to overwhelm the Mongol invaders.

Around nightfall, a typhoon caused the Mongol ship captains to suggest that the land force reembark in order to avoid the risk of being marooned on Japanese soil. By daybreak, only a few ships had not set out to sea. Those that had were destroyed by the storm. Some accounts offer casualty reports that suggest 200 Mongol ships were lost. However, small Japanese boats were much more swift and maneuverable than Mongol ships, and the Japanese were able to board the remaining ships of the crippled Mongol army. The samurai approached and boarded the ships under cover of darkness and fell on the invaders ferociously. In the small confines of the ships, during the predawn darkness, the Mongols (trained as cavalrymen and horse archers) were unable to bring their bows to bear effectively. However, the long, thin Japanese swords got stuck and snapped off in the thick, boiled leather armor of the Mongols, causing blacksmiths to reevaluate their swords, which led to the invention and spread of the now-famous katana in the 13th and 14th century. The katana was made shorter and thicker.

A story widely known in Japan is that back in Kamakura, Tokimune was overcome with fear when the invasion finally came, and wanting to overcome his cowardice, he asked Mugaku Sogen, his Zen master also known as Bukko, for advice. Bukko replied he had to sit in meditation to find the source of his cowardice in himself. Tokimune went to Bukko and said, "Finally there is the greatest happening of my life." Bukko asked, "How do you plan to face it?" Tokimune screamed, "Katsu!" ("Victory!") as if he wanted to scare all the enemies in front of him. Bukko responded with satisfaction, "It is true that the son of a lion roars as a lion!" Since that time, Tokimune was instrumental in spreading Zen and Bushido in Japan among the samurai.

Battle of Tsushima Island - Mongolian victory

On October 5, About 1,000 soldiers of Mongolian Army landed at Komoda Beach. Sukekuni So(宗助国), Shugodai of Tsushima Island was killed in action. The Mongolians slaughtered many dwellers of Tsushima island.

Battle of Iki Island - Mongolian victory

On October 14, Taira no Kagetaka(平景隆), Shugodai of Iki led about 100 soldiers. They were defeated by the Mongolian army and he committed suicide in Hidzume Castle(樋詰城). About 1,000 Japanese soldiers were killed there.

Battle of Hirato Island , Taka Island and Nokono Island - Mongolian victory

On October 16 to 17, the Mongolian army attacked the base of the Sashi Clan. Hundreds of Japanese soldiers and Husashi Sashi(佐志房), Tomaru Sashi(佐志留) and Isamu Sashi(佐志勇) were killed.

Battle of Akasaka - Japanese victory

The Mongolian Army landed on Sawara District and encamped at Akasaka. On seeing this situation, Takehusa Kikuchi(菊池武房) surprised the Mongolian army. The Mongolians escaped to Sohara, after losing about 100 soldiers.

Battle of Torikai-Gata - Japanese victory

Thousands of Mongolian soldiers were massed in Torikai-Gata. Suenaga Takezaki(竹崎季長), one of the Japanese commanders, attacked the Mongolian army and fought them. Soon, reinforcements led by Michiyasu Shiraisi(白石通泰) arrived and defeated the Mongolians soundly. The Mongolian casualties of this battle were about 3,500.

Withdrawal of Mongolian army

Due to the defeat in battle of Torikai-Gata, the Mongolian army was exhausted and withdrew to their ships. On seeing this situation, the Japanese army engaged in night attacks and killed many soldiers. Finally, Hong Dagu decided to withdraw to the Yuan-held continent. In the midst of withdrawal, they met a typhoon, most of their ships sank and many soldiers drowned.

Developments leading to the second invasion

Starting in 1275, the Shogunate increased efforts to defend against the second invasion, which they thought was sure to come. In addition to better organizing the samurai of Kyūshū, they ordered the construction of forts and a large stone wall (石塁, Sekirui), and other defensive structures at many potential landing points, including Hakata Bay, where a two meter high wall was constructed in 1276.

Religious services increased and the Hakozaki Shrine, having been destroyed by the Yuan forces, was rebuilt. A coastal watch was instituted and rewards were given to some 120 valiant samurai. There was even a plan for a raid on Goryeo (modern-day Korea) to be carried out by Shōni Tsunesuke, a general from Kyūshū, though this was never executed.

After the failed invasion, Kublai Khan was tired of being ignored and not being allowed to land, so five Yuan emissaries were dispatched in September 1275 and sent to Kyūshū, refusing to leave without a reply. Tokimune responded by having them sent to Kamakura and then beheading them. The graves of those five executed Yuan emissaries exist to this day at Jōryū Temple in Fujisawa, Kanagawa, near the Tatsunokuchi Execution Place in Kamakura. Then again on July 29, 1279, five more Yuan emissaries were sent in the same manner, and again beheaded, this time in Hakata. Expecting another invasion, on Feb 21, 1280, the Imperial Court ordered all temples and shrines to pray for victory over the Yuan.

Second invasion (1281)

In the spring of 1281, the Mongols sent two separate forces. An impressive force of 900 ships containing 40,000 Yuan troops set out from Masan, Korea, 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 by 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 Mongol fleet set sail, suffered heavy losses at Tsushima, and turned back. In the summer, the fleet took Iki-shima and moved on to Kyūshū, landing at several different locations. In a number of individual skirmishes, known collectively as the Kōan Campaign (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 with two-meter high walls, 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 and all 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 instead. 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.

Battle of Tsushima Island - Japanese victory

On May 21, the Mongolian Army landed on Tsushima island and invaded. They met fierce resistance there and later withdrew.

Battle of Shikano Island - Japanese victory

On the morning of June 8, the Japanese army divided their force into two and attacked along Umi no Nakamichi. The Japanese army lost 300 soldiers but defeated Hong Dagu, who nearly died in this battle, and Zhang Cheng.

On June 9 Zhang Cheng solidified the defense of his army but the Mongolian army was again defeated by the fierce Japanese attacks. After this defeat the Mongolian army escaped to Iki Island.

Battle of Iki Island - Japanese victory

On June 29, a Japanese army of approximately 10,000, led by the Matsura Clan, Ryuzoji Clan and Takagi Clan began an all-out attack on Iki Island. On July 2, Iekiyo Ryuzoji landed on Setoura beach and defeated the Mongolian army. As a result, the Mongolian army decided to abandon Iki Island and withdrew to Hirato Island.

Battle of Mikuriya - annihilation of Mongolian navy

On July 5, Suenaga Takesaki attacked and annihilated the Mongolian Navy. After this battle, most of the commanders of the Mongolian army escaped to their own country.

Battle of Taka Island - annihilation of Mongolian army

On July 7, there were about 100,000 soldiers of the Mongol army without commanders. Upon realizing this situation, the Japanese army attacked. Korechika Togo, Koretoo Togo, Sukekado Hujiwara and Nagahisa Shimazu defeated 100,000 soldiers. The Japanese took 20,000 to 30,000 prisoners in this battle. At the completion of this battle, Japan's victory was confirmed.

Military significance

From a military perspective, the failed invasions of Kublai Khan were the first of only three instances when the samurai fought foreign troops rather than amongst themselves; the others being Japanese invasions of Korea (1592–98) and the Japanese invasion of Ryukyu (1609). It is also the first time samurai clans fought for the sake of Japan itself instead of for more narrowly defined clan interests. The invasions also exposed the Japanese to an alien fighting style which, lacking the single combat that characterized traditional samurai combat, they saw as inferior. This difference is noted in the Hachiman Gudōkun:

According to our manner of fighting we must first call out by name someone from the enemy ranks, and then attack in single combat. But the Mongols took no notice at all of such conventions. They rushed forward all together in a mass, grappling with any individuals they could catch and killing them.

The Mongol method of advances and withdrawals accompanied by bells, drums and war cries was also unknown in Japan, as was the technique of Mongolian archers, which involved shooting arrows en masse into the air rather than long-ranged one-on-one combat. The Zen Buddhism of Hojo Tokimune and his Zen master Bukko had gained credibility beyond national boundaries, and the first mass followings of Zen teachings among samurai began to flourish.

The failed invasions also mark the first use of the word kamikaze ("Divine Wind"). The fact that the typhoon that helped Japan defeat the Mongol Navy in the first invasion occurred in late November, well after the normal Pacific typhoon season (May to October), perpetuated the Japanese belief that they would never be defeated or successfully invaded, which remained an important aspect of Japanese foreign policy until the very end of World War II. The failed invasions also demonstrated a weakness of the Mongols – the inability to mount naval invasions successfully (see also Mongol invasions of Vietnam.) After the death of Kublai, his successor, Temür Khan, unsuccessfully demanded the submission of Japan in 1295.

The Mongols and the Ashikaga shogunate of Japan made peace in the late 14th century during the reign of Toghon Temür, the last Yuan emperor in Khanbaliq. Long before the peace agreement, there was stable trade in East Asia under the dominance of the Mongols and Japan.

As a consequence of the destruction of the Mongol fleets, Japan's independence was guaranteed. Simultaneously, a power struggle within Japan led to the dominance of military governments and diminishing Imperial power.

Technological significance

The Mongol invasions are an early example of gunpowder warfare. One of the most notable technological innovations during the war was the use of explosive bombs. The bombs are known in Chinese as "thunder crash bombs" and were fired from catapults, inflicting damage on enemy soldiers. An illustration of a bomb is depicted in a Japanese scroll, showing their use by the Mongols against mounted samurai. Archaeological evidence of the use of gunpowder was finally confirmed when multiple shells of the explosive bombs were discovered in an underwater shipwreck off the shore of Japan by the Kyushu Okinawa Society for Underwater Archaeology. X-rays by Japanese scientists of the excavated shells provided proof that they contained gunpowder.