Blown Away? What the Evidence Says About the Mongol Invasions of Japan

Few stories in Japanese history are as tidy as the “divine wind.” Twice, the tale goes, the armies of Kublai Khan sailed for Japan, and twice the gods sent a typhoon to destroy them. The story is old, and it has been put to many uses. The evidence behind it is messier and, in some ways, more interesting: a warrior’s illustrated memoir, a coastal wall still turning up under Fukuoka, sediment cores from a lake in Kyushu, and the broken hulls of Yuan dynasty ships lying in the mud of Imari Bay.

This piece sorts what is documented, what is argued over, and what is legend.

Kublai Khan’s demands and the first attack (1274)

By the 1260s Kublai Khan ruled north China as the founder of the Yuan dynasty and had made the Korean kingdom of Goryeo a vassal. His court sent letters to Japan demanding that it enter into relations on Mongol terms. The Kamakura shogunate, the warrior government in eastern Japan, did not submit. These broad outlines are not in dispute.

In late 1274, in the Japanese era called Bun’ei, a Mongol, Korean, and north Chinese force sailed from Korea, attacked the islands of Tsushima and Iki, and then entered Hakata Bay in northern Kyushu. According to the historian Kawai Atsushi, the fleet arrived at dawn on 19 November, and by the following morning the ships were gone.¹ What happened in between, and why the fleet left, is where agreement ends.

The traditional account says a storm wrecked the fleet that night. Thomas D. Conlan, in In Little Need of Divine Intervention (2001), argues that the contemporary record does not support a catastrophic typhoon in 1274. In his reading, the invaders fought an indecisive day against local warriors, withdrew to their ships, and departed when the wind shifted, a change noted by a courtier in the capital rather than a disaster.² Other writers, following older Japanese scholarship, still describe ships lost to weather on the way home. Kawai notes that Japanese textbooks have offered a range of explanations, from storms to low morale and logistics.¹ The fairest summary is that the 1274 storm is contested: the Yuan force certainly withdrew quickly, and it may have met bad weather, but the idea that a typhoon alone ended the invasion rests on weak contemporary evidence.

The warrior who painted himself into history

The most vivid surviving source for both invasions is a pair of illustrated handscrolls known in Japanese as the Mōko Shūrai Ekotoba (“Illustrated account of the Mongol invasions”). They were commissioned by Takezaki Suenaga, a minor warrior from Higo province in Kyushu, who fought in both campaigns. Suenaga’s purpose was practical as much as commemorative: warriors were rewarded for documented service, and the scrolls record his deeds, his wounds, and his struggle to have them recognized.

Conlan’s book translates the scrolls’ text together with roughly seventy related administrative documents, and it reproduces a rarely seen copy that preserves scenes otherwise missing.²³ His central claim, stated in the title, is that Japanese warriors were capable of fighting the invaders to a standstill and did not need divine help. He also argues that the invading forces were smaller than the huge figures repeated in later histories.³

The scrolls are not a photograph of 1274. They have been cut, rearranged, copied, and retouched over the centuries. Bowdoin College’s digital edition lets readers compare historical copies side by side and explains how the scrolls were altered.⁴ Reviewers of Conlan’s edition, drawing on the Japanese scholar Satō Hiroo, point to details that appear to be later additions, including some scenery around Suenaga’s wounded horse and the famous image of an exploding Mongol bomb above him.³ That last point matters because the picture is often reproduced as proof of gunpowder weapons in 1274. The weapons were real (see below), but the painted scene may not be original.

The wall at Hakata

After 1274 the shogunate prepared for a return. Kyushu warriors were assigned to build and guard a stone barrier along the shore of Hakata Bay, today called the Genkō Bōrui (“Mongol invasion defensive wall”). Fukuoka City’s own tourism service presents the remaining sections as the wall that kept the invaders from landing,⁵ and new segments are still being found during construction, including at Kyushu University’s old Hakozaki campus.⁶ Reference accounts give its length as roughly 20 kilometers along the bay, though surviving stretches are short and partly reconstructed.

The wall’s effect in 1281 is reasonably well documented. The northern wing of the second invasion attacked Hakata Bay, could not establish a beachhead, and fell back to Iki. It then joined a much larger fleet from south China near Hirado, and the combined force moved toward Takashima and Imari Bay, a coast without a wall.⁷

1281: the storm that did happen

The second invasion, in the Kōan era, was larger and better planned. One force sailed from Korea; a second, drawn largely from the former Southern Song territories that Kublai had recently conquered, sailed from China. News coverage often repeats the traditional figure of 4,400 ships and 140,000 men,⁸ but these numbers are not secure, and Conlan argues for smaller forces.²

For roughly two months the invaders were kept at sea or on offshore islands by the wall and by Japanese raids on their anchored ships. Then, in mid-August 1281, a typhoon struck the fleet near Takashima.⁷ That storm is documented in Japanese sources and is not seriously disputed. What is disputed is how many ships and men it destroyed, and whether the invasion would have failed anyway.

Geology has added an independent line of evidence. In 2015 a team led by Jonathan Woodruff published a 2,000-year record of typhoon overwash from a coastal lake in Kyushu near the invasion coast. Two of the largest storm layers date to roughly the right period, and the authors suggest that the thirteenth century saw more typhoons steered toward Japan than today.⁹¹⁰ The authors are careful: radiocarbon dating cannot pin a layer to a single year, and they note that written accounts of these storms are prone to exaggeration.⁹ The lake record shows that intense typhoons hit the region in that era; it does not settle whether one struck in 1274.

What lies under Imari Bay

The waters off Takashima, at the mouth of Imari Bay in Nagasaki Prefecture, are where the 1281 fleet came to grief, and they have become one of East Asia’s best-known underwater sites. Local fishermen had long brought up pots and weapons there. A bronze seal inscribed in Chinese and in the Phags-pa script used by the Yuan state, apparently belonging to a unit commander, was found on the Kōzaki shore in 1974.¹¹¹² Systematic underwater survey began in the 1980s.¹³

Much of the early fieldwork was led by Kenzo Hayashida of the Kyushu Okinawa Society for Underwater Archaeology. During harbor works at Kōzaki in 1994, his team recovered large wooden anchors with stone stocks; divers also found a helmet and ceramic projectile bombs.¹²¹¹ These bombs, called tetsuhau in Japanese sources, are hollow ceramic spheres. One measured about 13 centimeters across, and a CT scan at Kyushu University showed it was packed with metal and ceramic fragments, making it a fragmentation weapon.¹² The bombs confirm what the scroll appears to show, regardless of whether the painted image was retouched.

A full seabed survey began in 2005, and a team under Yoshifumi Ikeda of the University of the Ryukyus used sonar to map more than a hundred anomalies.¹¹ In 2011 the team announced a hull lying about a meter beneath the seabed in 20 to 25 meters of water, with a keel section about 12 meters long and associated weapons, Yuan pottery, and brick ballast.¹⁴ A second wreck was located in 2014 about 1.7 kilometers away¹⁵ and confirmed in 2015.⁸ A Japanese government research report from 2015 describes two identified hulls, both apparently built in southern China.¹⁶ (Press reports are inconsistent about whether there are two or three vessels.) In 2012 the Takashima Kōzaki area became Japan’s first underwater national historic site.¹¹

The ship timbers have changed the question from “did a storm sink the fleet?” to “what kind of fleet was it?” Randall Sasaki’s Texas A&M thesis (2008), revised as The Origins of the Lost Fleet of the Mongol Empire (2015), worked through more than 500 hull fragments, most badly degraded. He links different construction traditions to Korea, the Yangtze region, and Fujian, and he cautions against a popular explanation: that the fleet sank because it was made of flimsy river boats. Some ships, he argues, were strongly built, and evidence of repair does not by itself prove weak construction.¹⁷ James Delgado’s Khubilai Khan’s Lost Fleet (2008) offers a broader account that combines the wrecks, the scrolls, and written records.¹⁸ Jun Kimura, Sasaki, and colleagues have since treated Takashima alongside the Bạch Đằng River battlefield in Vietnam, where Kublai’s forces were also defeated, as a case of “naval battlefield archaeology.”¹⁹

How a wind became a weapon

The word kamikaze, “divine wind,” did not come from the warriors on the beaches. It grew from the claims of religious institutions. The court and the shogunate ordered temples and shrines to pray for the realm’s protection, and after 1281 those institutions argued that their prayers had summoned the storms.²⁰ They had reason to: claims of divine service could be traded for land and patronage, and the estates of Usa Hachiman Shrine, for example, were restored after its role was stressed.²¹ Conlan’s book shows the same reward-seeking at work among warriors like Suenaga, who pressed their claims on paper and in paint.²³ The legend therefore first appears as a religious and political argument made in the decades after the invasions, competing with warriors’ own accounts of how the fighting went.

The story took on a new life centuries later. In the early twentieth century, nationalist education promoted Japan as a land protected by the gods, and wartime textbooks gave the divine winds pride of place. The Kyūshū University historian Hattori Hideo has described these lessons as propaganda presented as history, and argues that medieval warriors themselves never embraced the myth.²¹ In 1944 and 1945 the name was attached to the suicide units of Japan’s navy and army air forces, completing the shift from a story about a storm to a call for self-sacrifice.

What can be said with confidence? The invasions of 1274 and 1281 were real, large, and costly. A powerful typhoon struck the second fleet off Takashima, and lake sediments suggest the era was stormy. Whether a storm had any decisive role in 1274 remains open. And in both campaigns, the documents, the wall, and the seabed point to the same thing Takezaki Suenaga wanted his viewers to see: Japan’s defense was mostly the work of people.

Footnotes

1. Kawai, “Saved by the Wind?”, Nippon.com. ↩ ↩²

2. Conlan 2001, introduction and interpretive essay. ↩ ↩² ↩³ ↩⁴

3. Wakabayashi 2004, JJRS 31(1): 209-213. ↩ ↩² ↩³ ↩⁴

4. Bowdoin College, scroll comparison viewer and guided tour. ↩

5. Go Fukuoka, “The Wall that Drove Back the Mongols.” ↩

6. Fukuoka Now, Hakozaki campus wall discovery. ↩

7. Association for Asian Studies, Eurasian Maritime History case study. ↩ ↩²

8. Archaeology, “Second ‘Kamikaze’ Shipwreck Discovered,” 2015. ↩ ↩²

9. Woodruff et al. 2015, Geology 43(1): 91-94. ↩ ↩²

10. Nature 516: 290 (2014). ↩

11. Nippon.com, “Ships on the Seabed.” ↩ ↩² ↩³ ↩⁴

12. Archaeology 56(1), “Relics of the Kamikaze.” ↩ ↩² ↩³

13. Kimura 2006, Bulletin AIMA 30: 7-13. ↩

14. Phys.org, October 2011. ↩

15. Archaeology, 3 October 2014. ↩

16. KAKEN Project 23222002, final report (FY2015). ↩

17. Sasaki 2015; see also Sasaki 2008 thesis. ↩

18. Delgado 2008. ↩

19. Kimura et al. 2014, IJNA 43(1): 76-86. ↩

20. Japan Society, “Japan’s Medieval Age.” ↩

21. Nippon.com, “Myth of the Kamikaze” (Hattori Hideo). ↩ ↩²