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When the legendary Mongol conqueror sought to invade Japan, he didn’t expect defeat to arrive with the wind.

For more than a decade maritime archaeologists working in the murky waters off Takashima Island on Japan’s Kyushu coast have raised shattered ships’ timbers, armament, provisions, and the remains of lost soldiers and sailors associated with one of history’s most significant naval invasions—Kublai Khan’s 1281 assault on Japan.

The invasion fleet comprised thousands of ships and hundreds of thousands of men—an operation not again equaled until the 1944 Allied landings in Normandy. The invasion is perhaps better known, however, for the fleet’s destruction by a legendary typhoon known as kamikaze (Japanese for “divine wind”). The legend of the kamikaze resonated again in the 20th century, when a desperate Japan invoked the term as a tokko, or suicide tactic, at the end of the Pacific War in 1944 and 1945.

The search for the remains of Kublai Khan’s lost fleet began in 1980 when Torao Mozai, an engineering professor and veteran of the World War II Imperial Japanese Navy, set out to learn whether the story that had inspired his shipmates and his nation was a myth.

Mozai knew of the recorded invasions by Kublai Khan in 1274 and 1281. Marco Polo, a visitor at the khan’s court, had written of Kublai’s failed efforts to conquer Japan and how the khan’s commanders had blamed storms for their failure. Mozai also knew of Japan’s enduring legend of the invasions, and that shrines in Fukuoka on Hakata Bay, site of one of the battles, commemorate Japan’s godsent victory. At Tokyo’s Museum of the Imperial Collections he found a late 13th century scroll that depicts samurai warrior Takezaki Suenaga in combat both on the beach and aboard the invading Mongols’ ships. Whether the legend and the scroll were accurate was another matter.

Mozai was determined to find Kublai Khan’s sunken fleet and, through careful study of the physical evidence, determine what had actually happened. Mozai started his search in the early 1980s with the Kyushu fishermen, who, like their ancestors before them, had hauled artifacts to the surface in their nets. Swords, pots, a bronze Buddha and an inscribed bronze seal that had belonged to one of the khan’s generals all appeared to be remnants of the invading fleet, and they all pointed to the waters of Imari Bay, south of Fukuoka and off the island of Takashima, as the site where Kublai’s lost fleet littered the seafloor. Using sonar, Mozai pinpointed areas where he believed the Mongol ships lay beneath a thick layer of mud.

Mozai’s survey paved the way for more extensive investigations by a team of Japanese maritime archaeologists led by Kenzo Hayashida, who in the 1990s began excavating the seafloor to find the broken ships. The dig continued through the early 2000s, as thousands of artifacts emerged from their long burial, providing both a tangible link to a legendary event and insights into the invading forces, their ships and possible reasons for the khan’s defeat.

The story of Kublai Khan’s lost fleet begins more than a decade before Mongol ships first sailed for Japan, when Kublai gained the mantle of great khan of the Mongols and continued the ambitious invasions launched by his famous grandfather, Genghis Khan (c. 1162–1227), to extend Mongol power across the known world.

Under Genghis’ leadership the Mongols surged out of the Eurasian steppes to forge the largest contiguous empire the world has ever seen. Genghis consolidated the Mongols, long a disparate and feuding group of clans of horsemen, into a formidable cavalry that launched a series of bold strikes west into the Middle East and then into Europe. By 1242 Mongol invaders stood at the gates of Western Europe after occupying much of Russia and sweeping into Hungary. Fierce resistance and their own disorder eventually led them to retreat not only from Europe but also from the Middle East; the Egyptian Mamluks halted the Mongol advance south in 1260 and retook Mongol-occupied Mesopotamia. The Mongols then turned their attention east, subjugating Korea, northern China and, finally, the Sung empire of southern China.

The Sung Dynasty, then the world’s mightiest naval power, had battled northern invaders for centuries. Trading regularly with Asia, Indonesia, India and the Arabs, it was a wealthy state but weakened by corruption and internal dissension. When Kublai gained the Mongol throne in 1260, he resumed the campaign against the Sung that his grandfather, father, uncles and cousins had begun. Kublai succeeded in conquering China by swelling his ranks with Sung defectors and adding Sung ships to a fleet he was amassing to invade China’s rivers and coasts. Adaptable and quick to assimilate his enemy’s technology and strengths, Kublai had by 1279 defeated the last Sung emperor. His new empire, centered in China as the Yuan Dynasty, now controlled the largest country on earth.

Expansion into other regions of the Far East was possible, but only through naval action. Thus Kublai turned to the large fleet he had used to defeat the Sung. He also wisely continued the Sung policy of expansive maritime trade, using his navy as both a tool of trade and a means of Mongol expansion.

The shogunate of Japan was the khan’s first overseas target.

The Japanese were regular trading partners of the Sung and, therefore, no strangers to the Mongols. Even as he waged his war against the Chinese, Kublai Khan sent envoys to the Japanese in 1266 and 1268 to demand their subservience— and to cut off vital trade that was filling the Sung court’s coffers. The bakufu, or Japanese military dictatorship, ignored the Mongol demands. Kublai’s response was to order his vassals in the subjugated Korean state, Koryo, to build a vast fleet of some 900 ships and prepare to invade Japan. For centuries a lucrative trade route, the relatively narrow Korea Strait—spanning some 120 miles between Koryo and Japan’s Kyushu coast—would now be a highway of war.

The khan’s fleet departed Koryo on Oct. 3, 1274, with 23,000 Mongol, Chinese and Korean soldiers and 7,000 sailors aboard. Two days later the force overwhelmed the 80-man island garrison of Tsushima, in the middle of the strait. Next to fall was the island garrison of Iki, closer to the Japanese coast. The fleet attacked the coastal port of Hirado on October 14, then moved north to land at various points along Hakata Bay, near modern-day Fukuoka. Thanks to spies in Koryo, the Japanese had been forewarned of the Mongol advance and had rushed groups of samurai and their retainers to Hakata Bay. Japanese historians estimate that some 6,000 defenders stood ready to fight the much larger invading army.

The battle was unequal in numbers and in tactics. The Mongols advanced en masse and fought as a unit, while the samurai, true to their code, ventured out to fight individual duels. In a week of fighting the Japanese slowly gave way. By October 20 the Japanese had retreated from the beach, falling back 10 miles to an ancient abandoned fortress at Mizuki.

Things were not all going the khan’s way, however. Japanese reinforcements were pouring in from the surrounding countryside, the senior Mongol commander was wounded, and sailors aboard the ships were wary of an incoming storm that threatened the fleet in its crowded anchorage along the rocky shores of Hakata Bay. Deciding a strategic withdrawal was in order, the invaders burned the town of Hakata, reboarded their ships and departed. The storm grounded some 50 ships of the Mongol fleet, which the Japanese then boarded, executing the crews. But the loss to the khan was not catastrophic, and he had succeeded in cutting trade between Japan and Sung China.

Alarmed at their near defeat, the bakufu ordered defenses built at Hakata Bay and troops massed to meet another invasion. Laborers erected a 25-mile-long, 5- to 9-foothigh stone wall, set back some 150 feet from the beach, and the samurai organized their vassals into a compulsory defense force. The bakufu also requisitioned small fishing and trading vessels to build a coastal naval force. Angered at the reticence of some samurai to engage the Mongols in battle, the bakufu replaced many of the feudal lords around Hakata Bay with samurai allied with the ruling shogun.

Despite his initial setback, Kublai Khan did not forget Japan. In April 1275 he sent an envoy to Nagato demanding a Japanese capitulation. The bakufu let the envoy and his entourage cool their heels for four months, then summoned them to the shogunal seat of Kamakura for summary execution. Kublai renewed his appeal for surrender in June 1279, even as the last remnants of the Sung dynasty crumbled before the Mongol onslaught in China. But Mongol power obviously still did not impress the bakufu, who this time executed the khan’s emissaries on the beach at Hakata as they landed to negotiate. Furious, Kublai ordered Koryo to build a new fleet of 900 ships and assemble an invasion force of 40,000 Mongol and Korean warriors and 17,000 sailors. In China the khan assembled an additional fleet of nearly 3,500 ships and an invasion force of 100,000 Chinese warriors.

Kublai ordered the two fleets—the Koryo Eastern Route Division and Chinese Chiang-nan Division—to rendezvous at Iki and coordinate their attack. The Eastern Route Division sailed first on May 3, 1281, retaking Iki on June 10. But within a week, without waiting for the arrival of the Chiangnan Division, the impatient Eastern Route commanders sailed for Hakata Bay. The stone defensive wall thwarted a landing, so the troops instead occupied Shika Island in the middle of the bay. The Japanese used small coastaldefense vessels to harass the Mongol fleet, slipping armed samurai aboard the enemy ships to kill their crews and soldiers. Badly mauled, the Eastern Route Division retreated to Iki, the Japanese in hot pursuit.

The Chiang-nan Division finally sailed from China in mid-June, joining forces with the battered Eastern Route Division at Hirado. In an attempt to bypass the defenses at Hakata Bay, the combined Mongol fleet struck the garrison on the small island of Takashima in Imari Bay, some 30 miles south of Hakata, and then landed its invasion force. The Japanese were waiting ashore, and a two-week battle raged across the rugged countryside. Meanwhile, the Mongol crews, in preparation for the inevitable assault by Japanese coastal craft, chained their ships together to form a massive floating fortress, complete with a planked walkway. The Japanese vessels—including fire ships—did strike the floating Mongol fortress, but to little effect. The principal fight was ashore, where losses on both sides mounted.

As the Mongols prepared to launch their final offensive, legend has it Emperor Kameyama—by tradition the descendant of gods and a god himself—beseeched his ancestors for Japan’s deliverance. His prayer was apparently answered on July 30, when a massive storm smashed into the Mongol ships. Legends describe the kamikaze as “a green dragon” that “raised its head from the waves” as “sulfurous flames filled the firmament.” Driving rain, high winds and storm-driven waves lashed the sprawling Mongol fleet as it tried to flee through the narrow harbor entrance.

As the khan’s visitor Marco Polo later related the story:

Such a gale was blowing from the north that the troops declared that, if they did not get away, all their ships would be wrecked. So they all embarked and left the island and put out to sea.…When they had sailed about four miles, the gale began to freshen, and there was such a crowd of ships that many of them were smashed by colliding with one another. Those that were not jammed together with others but had enough sea room escaped shipwreck. Those that succeeded in clearing this island made good their escape. The others who failed to get clear were driven aground by the gale.

According to legend, the kamikaze sank nearly 4,000 Mongol ships and drowned some 100,000 men. The exultant samurai dragged exhausted survivors ashore and killed them. They then rounded up the stranded Mongol invaders and executed them. The shores were littered with debris and bodies. According to Japanese accounts, the entrance to Imari Bay was so clogged that “a person could walk across from one point of land to another on a mass of wreckage.”

Kublai Khan considered a third invasion of Japan but dropped his plans in favor of a sea and land invasion of Vietnam and a military mission to Java. The story of the khan’s invasion of Japan, now firmly part of the island nation’s history and legend, lasted through the centuries and 700 years later inspired the archaeological quest to learn exactly what had happened in 1274 and 1281.

The artifacts divers have pulled from the seafloor since the 1980s speak both to the khan’s preparations—the types of ships he deployed, the composition of his forces, the arms they carried—and to the reasons for their defeat.

Japanese maritime archaeologists working in 40 feet of water off Takashima’s Kozaki Harbor dug through 20 feet of gelatinous mud to reach the seabed of 700 years ago. There, a jigsaw puzzle of broken timbers, ceramics, rust-encrusted iron and other finds required painstaking mapping and recovery, particularly since the centuries of immersion had rendered much of the wood the consistency of cheese.

The wide dispersion of the finds suggested a violent end to the fleet, perhaps through a storm surge. What was unclear to Kenzo Hayashida was whether the jumbled wreckage was the result of one massive storm or several centuries of storms. His team eventually concluded that a single storm had indeed wrecked the fleet, but that the level of destruction was due to subsequent storms on a coast frequently lashed by powerful seasonal typhoons. They also noted fire damage to certain timbers, suggesting that at least some of the ships had burned before sinking.

The broken bones of a soldier amid what appear to be his weapons, armor and personal possessions offer compelling evidence as to a sudden loss. Not much was left of the soldier—just the top of his skull and a hip. Fragments of red leather in the mud represent the remains of a suit of lamellar armor, and a nearby helmet may well be his. Divers also found a sword, two bundles of iron crossbow bolts and a lone rice bowl. Written on the latter’s base, in the time-honored tradition of soldiers and sailors, were the name WANG and the rank COMMANDER OF 100. Wang is a common surname even today in southern coastal China, and it indicates that this centurion in Kublai Khan’s army was a subjugated Chinese warrior incorporated into the Mongol forces.

Most of the armament at the site is from China, as are the ships, according to analyses of the surviving timbers. The archaeologists also traced the large oak-and-granite anchors to China. In all, Hayashida’s team found that 99 percent of the recovered artifacts were of Chinese origin; the remaining 1 percent could indeed be Mongol.

Among the most surprising finds was a series of ceramic bombs of a type historians had not thought existed at the time. One panel of the painted scroll of samurai Takezaki Suenaga depicts him falling from his horse, both rider and mount bleeding, as an aerial bomb explodes above him. Some historians had suggested the bomb was a later addition, and that Suenaga was in fact wounded by a flight of arrows. But archaeologists at Kozaki recovered several fragments of such bombs, known as tetsuhau, as well as intact examples. X-rays revealed these lethal Chinese-made weapons to be loaded with gunpowder and bits of metal shrapnel.

Randall Sasaki, a Texas A&M University graduate student who joined Hayashida’s team, made a detailed study of the ships and digitally reconstructed the Chinese-built fleet of troop transports and supply ships that merged with Korean-made shallowdraft landing craft to assault Japan’s shores in 1281. He discovered that the fleet had been hastily assembled, with some vessels showing their age and others in poor repair. But Sasaki also found ships that were the epitome of exceptional Chinese naval construction, many likely veterans of the Sung navy Kublai Khan had assembled to conquer China.

While archaeologists have excavated only a portion of the vast naval battlefield of 1281, they can now offer a reconstruction of the failed invasion that separates fact from legend. Kublai Khan’s forces embarked on an armada of ships of different types. Assembling off the Japanese coast, they were denied a landing spot of sufficient size by waiting samurai and the stone defensive wall that ringed the site of the 1274 invasion. From small boats the samurai harassed the invading fleet, forcing it to anchor close to shore in tight quarters. Fire ships took out some of the Mongol transports, and as the battle of attrition dragged on, a seasonal typhoon’s fortuitous arrival smashed into the larger ships, sending their crews and cargoes to the bottom. The lighter ships had more room to maneuver and were able to escape the harbor. (Only a handful of timbers Sasaki analyzed appear to be from the Korean-built landing craft.)

To the victorious Japanese the storm seemed god-sent, and while the legend of the kamikaze that resonated through Japanese history over the centuries inspired the suicidal—and ultimately futile—aerial assaults against Allied ships in the latter stages of World War II, it also prompted the decades-long quest to find Kublai Khan’s lost fleet and learn what really happened so long ago off Japan’s Kyushu coast.


For further reading James Delgado recommends his own Khubilai Khan’s Lost Fleet: In Search of a Legendary Armada.

Originally published in the July 2011 issue of Military History. To subscribe, click here