Khublai Khan, grandson of Ghingis Khan, sent an invasion force to Japan twice. Once in 1274 and once in 1281. According to legend, a storm hit the Mongolians just as they reached Japan and repelled their invasion. Thus was born the legend that “kamikaze” – “divine wind” – was protecting Japan.
The Japanese were certainly disadvantaged. In the first invasion, Khan sent 26 thousand Mongolian and Korean troops on 900 ships. The defenders are estimated to have numbered 5 to 10 thousand. The mongolians used gunpowder in the form of bombs (guns had yet to be invented) and fought in groups. The Japanese had a custom of fighting in duels as the rest of the army watched in the background. It was something of a formal ritual. Champion warriors of each team would come forward and give long-winded introductions of themselves before engaging in single combat in front of the troops. Mongolians were more practical about war and they did not care for ritualistic duels. It is recorded that many Japanese soldiers were killed while they were trying to announce their names. The bombs startled the Japanese and their horses. The Mongolians used extremely long ranged short bows with poisoned arrowheads. Also, the long sweeping swords favored by the Japanese of the time tended to break on the hard Mongolian armor. After the first Mongolian invasion, the Japanese swords were shortened and thickened and took the shape that they have today.
The Mongolians had sent several envoys to Japan prior to the invasion demanding surrender. The whole of Japan was ordered by the emperor to perform magical rites to curse and defeat the enemy. So when the Mongolians mysteriously terminated the first invasion, it was natural for the defenders to think that all the cursing paid off and that some divine force had helped them out.
I grew up thinking that there really was a storm that defeated the Mongolians and that Japan was just plain lucky. But there actually was no record of a storm in the first invasion, neither in Japanese nor Chinese accounts of the event. The Japanese, it seems, looked out to sea one morning and discovered that the Mongolian ships were gone.
The second invasion consisted of 40 thousand Mongolian-Korean troops and 100 thousand Chinese troops on 4400 ships. This must have been the biggest landing operation in history up to that time. So if it was just dumb luck that repelled the Mongolians first time around, why did they bother to send five times as many troops the second time?
After the first invasion, Khan sent ambassadors to Japan twice. Both times they were all beheaded. So, Khan had good reason to be pissed off. But that doesn’t explain why he spent so much money to flatten an inferior force that got off on a lucky break.
The second time around, Japan was clearly lucky. The 40 thousand troops reached the coast of Hiraga in early June, but the 100 thousand troops from Mongolian occupied China was delayed because the Chinese commander fell ill (or so he said) and didn’t arrive until July. During this time, the 40 thousand that left the Korean penninsula anchored off Hiraga and waited there without landing. That’s right, 40 thousand people were living on the water for a whole month. The effect on morale must have been awful, not to mention the inevitable logistic problems of providing food and water. They made some sorties to Shikanoshima in mid June, but did not get foothold on shore and went back to their ships by night. By the time the reinforcements from China arrived, it was storm season. Due to mix of foul weather and Japanese resistance, the Mongolians lost three fourths of their forces and retreated to Korea. A third invasion was planned but never realized due to unrest within Khublai Khan’s empire.
So what accounted for this strange behavior of the Mongolian invaders at the second invasion? Why did the Mongolians wait so long for reinforcements to arrive and why did they stay on their ships and not camp on land?
Let’s look at what happened in the first invasion.
The Mongolian ships appeared off Hakata on October 19th, 1274. Upon dawn on October 20th, the 26 thousand invasion troops landed. The Japanese who were waiting for them were outnumbered perhaps by 3 to 1. The defenders resisted fiercely, but with the combination of superior weapons and tactics and greater numbers, the invasion troops advanced. The defenders retreated to Mizuki fortress. They were furious that the Mongolians did not follow the protocols of war. They made an oath to fight until every Mongolian was dead. The Japanese turned to the offensive again after nightfall and struck in the cover of darkness. On the morning of the 21st, they looked out to sea and found that all 900 ships of the invasion troops had disappeared. The samurai were left scratching their heads as to what happened. They concluded that it must have been divine intervention. The invaders left behind 13 thousand of their own dead.