The Mongol invasions of Japan

By Bloodswan

Japanese history proudly speaks of two Mongol invasions of Japan. The first invasion took place in 1274 with the second occurring in 1281. Both of these invasions were driven back by the bravery of the samurai and the supposed intervention of the gods. The Mongol invasions of Japan were the first only time a foreign power had attempted to invade Japan until the Western colonial era. They were also the most ambitious of Khubilai's invasion plans. Suddenly the greatest cavalry the world had ever seen decided that they were marines!

The first invasion

In 1261, 1271 and 1274 the Mongol emperor of the newly founded Yuan dynasty of China, Khubilai Khan sent envoys to Japan with demands for tribute. The Japanese imperial court had been of the opinion that China was a great country and worthy of respect but the government had been taken over by a new ambitious samurai government. Their opinions of the Mongols came largely from expatriate Chinese monks who had escaped Song China and had been welcomed by the Kamakura regime. These monks had become quite influential and many of these monks were obviously quite anti-Mongolian. The imperial court in Kyoto considered the demands of tribute but a young regent by the name of Hojo Tokimune was determined to refuse. He called on the samurai to set side their differences and unite to defend Japan from this new threat from across the sea. Had the new Bakufu (government institution under the shogunate) known of the overwhelming power of the Mongols then perhaps their decision would have been different.

The first operation which took place in 1274 was more of a reconnaissance mission than an actual full scale invasion but none the less the Mongol army was larger than would have been expected if it was to be a mere raid. Mongol maritime resources had clearly been aided by the capture of Korea and Song China and Khubilai Khan order 900 ships to be built specifically for the campaign. These were to transport the 5,000 Mongol and 8,000 Korean advance troops as well as the main body of 15,000 Mongol, Chinese and Jurchen troops. The crew would have numbered a further 15,000 making a total of around 43,000 men for the campaign.

The Mongols set sail from Busan in October 1274. The Mongols ravaged the islands of Tsushima and Iki where their cruelty is depicted on a Nichiren memorial site at Hakata.

Landing in Hakata Bay in northern Kyushu, the Mongols were met by a handful of samurai. One young horseman came out from their line and shouted something incomprehensible. He then shot a whistling arrow and charged towards the Mongol ranks only to fall under the instant shower of Mongol arrows. To the samurai it was custom that to begin a battle someone had to introduce himself and fire a whistling arrow but this custom was lost on the Mongols despite the fact this may even have been an ancient Mongolian tradition. Mongol attachments came ashore at various parts of the bay.

The difference in fighting styles between the two armies dismayed the samurai at first. The samurai of the Kamakura period were used to fairly rigid conventions governing the actions and behaviour of warriors but now they faced a highly disciplined and utterly ruthless foe that controlled tactical manoeuvres and fought en-masse.

The Mongols also brought with them a weapon that terrified the samurai. In addition to the clouds of arrows fired which the Japanese were also not accustomed to, the Mongols also brought with them explosive bombs. These bombs were flung from trebuchets. An account from Hachiman Gudokun reads "The commanding general kept his position on high ground, and directed the various detachments as need be with signals from hand drums. But whenever the Mongol soldiers took flight they sent iron bomb shells flying against us which made our side dizzy and confused. Our soldiers were frightened out of their wits by the thundering explosions, their eyes blinded, their ears deafened, so that they could hardly distinguish east from west." These "mighty iron balls" were flung and "rolled down the hills like cartwheels, sounded like thunder" and when they exploded "looked like bolts of lightning". The use of these bombs is depicted on a prominent section of the Moko Shurai Ekotoba (Mongol invasion scroll) whereby a certain Takenaga Sueaki is shown charging the Mongol line only to have his horse hit by arrows and terrified by explosions. The Mongol shock tactics definitely worked in the opening engagement between the two armies.

Having suffered severe losses, the Kyushu samurai retreated inland to Dazaifu where they planned to make a last stand behind some ancient fortifications hoping for the arrival of reinforcements. The Mongols however chose only to hold the shore and return to their ships for the night. Despite their advantages, the Mongols seemed to have been shaken by the bravery of individual samurai attacks. Another factor in this decision was the poor morale of the Korean troops. It was even claimed that the Koreans had deliberately sabotaged some of their own ships. These issues coupled with the threat of Japanese reinforcements ambushing them at night on unfamiliar ground led the Mongols to take refuge within their ships.

That night a fierce storm blew up and severely damaged the fleet. Some Mongol soldiers were left on the Japanese coast and either captured or killed the following day. The captives were taken back to imperial court at Kyoto. The Mongols set sail back to Korea taking over a month to do so. The first Mongol invasion on the mainland had lasted one day and resulted in the loss of 13,000 soldiers, including a high-ranking Korean general and 200 ships.

There has been some doubt over the storm theory in recent times for a number of reasons. Firstly, it occurred in November which is out of typhoon season, secondly several Japanese accounts do not mention a storm although others do and thirdly an account by a Mongolian general, Liu Fu-Heng states that the withdrawal was purely tactical because they had ran out of arrows. The third reason is highly unlikely though and Liu also mentions confronting a Japanese army of 100,000 which is also probably greatly exaggerated. Having lost one third of their force in just a day it is interesting to speculate how many were killed by the samurai themselves. If the storm theory is discounted then the number must have been high indeed. Whatever happened it can not be denied that the bravery and martial skills of the samurai turned the opening raid into a pyrrhic victory for the Mongol forces.

The second invasion

Khubilai never saw the first invasion as a disaster. He was however preoccupied with the final conquest of Song China so Japan was not his priority. By contrast, the Japanese were in a state of alert. Religious activity in Japan increased and the symbolic Hakozaki shrine was rebuilt. 120 warriors who had shown their courage and bravery at Hakata Bay were rewarded and a coastal guard was formed. The Japanese had also planned a raid into Korea led by a Kyushu general named Shoni Tsunesuke but it never eventuated. In 1276 a defensive wall was ordered to be built by the regent Hojo Tokimune at Hakata Bay. The wall was over two metres in height and made of stone.

In 1279 the Mongols had extended their success into southern China and Japan was once again on Khubilai's agenda. The second invasion would be held on a far greater scale than the previous one. 900 ships were ordered from Korea with another order of war ships being constructed in southern China. Overall command of the invasion was given to the Mongol general Arakhan. The Mongol forces were divided into two armies. The plan was for the two armies to meet up before attacking but it did not go according to Khubilai's plan.

In July 1281, the eastern army which carried 25,000 soldiers and 15,000 sailors aboard 900 ships attacked Tsuhima and Iki before attempting to land at Hakata Bay without reinforcements. The Mongols launched attacks along the bay for about a week. The Japanese would respond to each attack with night raids. The Japanese ships would carry between 10 - 15 samurai and would close on the Mongol ships under the over of darkness. When the ships were close enough the ship's mast would be lowered to act as a bridge and the samurai would close in on the Mongol crew. The samurai excelled in close-quarter fighting and the Korean, Mongol and Chinese were no match for them in such tight quarters. On one occasion 30 samurai swam out to a Mongol vessel, decapitated the entire crew and swam back. Kusano Jiro led an attack in broad daylight and set a ship on fire even though he had his left arm cut off in the process. Kono Michiari also led a daylight raid in which the Mongols were led to believe they were coming to surrender. Instead of surrender Kono and his samurai boarded the vessel and captured a high-ranking general. These raids began unsettling the Mongols.

The Mongols also attacked Shiga island just off the coast of Hakata Bay but were met with fierce resistance by the Japanese under Otomo Yasuyori and Adachi Morimune. Having failing to make any ground the Mongols decided to anchor close offshore. The Mongols threw stones at the Japanese vessels using catapults but the bravery and ferocity of the samurai attacks led the Mongols to withdraw to Iki island and await the southern contingent's arrival from China. The Mongol fleet anchored off Takashima island to replenish their stocks and treat their wounded. It was here where the Mongols suffered from the weather. July is the wet season in Japan and the hot, wet, cramped conditions on board rotted the rations and killed some 3,000 Mongols. With their morale severely weakened, they were forced to wait a month on their rotting and stinking ships for the arrival of the southern fleet.

The huge southern armada (perhaps four times as strong as the eastern fleet) began arriving in various parts around the Japanese coast in early August. The sheer size of the southern fleet which carried as many Chinese as Mongols made the second Mongol invasion of Japan one of the largest naval operations of all time. The two armies finally met up at Takashima island where the Japanese launched a bold raid on the Mongol fleet which lasted the whole day and night. Eventually the Japanese were driven off by the sheer weight of the Mongol armies. A massive assault on Hakata Bay now looked inevitable.

The Kamikaze

On August 22 the southern fleet was destroyed by what the Japanese called the kamikaze or "divine wind". A typhoon had just swept through the Japanese coast and forced by the Japanese to stay in their ships but unable to drop anchor the Mongol fleet was obliterated. Possibly 4,000 vessels were sank drowning a total of about 30,000 men. Korean casualties were almost 30% but the Mongol and Chinese casualties were between 60 - 90 %.

It is also now believed that the destruction of the Mongol fleet was greatly facilitated by two additional factors. Most of the southern invasion force was composed of hastily-acquired flat-bottomed Chinese riverboats. Unlike ocean-going ships, which have a curved keel to prevent capsizing, these river boats had flat bottoms. Such ships cannot deal with the high seas let alone a massive typhoon. In addition, the true ocean-going ships in Khubilai's fleet which had been constructed by the Koreans may have been deliberately sabotaged. Fatal flaws such as poorly constructed joints and weak nails have been found in many of these ships.

The Japanese believed that the divine wind had came to destroy the foreign invaders and this also would have been justified by their increased religious activity during the invasions.

The eastern fleet did not suffer the same fate as the southern fleet and now the generals argued over whether or not the invasion should continue. The Mongol generals demanded that the campaign continue but the Chinese generals were unwilling. The Chinese commander Fan Wen-hu transferred to a safe ship and returned to China.

Tens of thousands of men were left behind with the wreckage as the remains of the fleet sailed home. These troops were hunted down by the samurai. All Mongols and Koreans were killed but many of the Chinese were not executed. It was believed because they were not willing participants in the war. They were probably also helped by those Chinese monks who had become quite influential since fleeing the Mongols from Song China.

Khubilai Khan had planned for a third invasion but a drain on military resources due to various uprisings and rebellions forced him to cancel any further plans for the conquest of Japan.

The Mongol invasions were an important part of Japanese history. For the first time in their history the samurai had put aside their differences to drive away a foreign invader. After the coastal defences were put off alert in 1312 the samurai went back to their time-honoured tradition of fighting each other and it was not until several centuries later that the notion of a unified Japan was raised again.


Genghis Khan and the Mongol conquests by Stephen Turnbull
The samurai by Mitsuo Kure
The samurai by Anthony J Bryant
Early samurai by Anthony J Bryant
Various internet sources