The rise of the Mongols was a key event in the evolution of gunpowder technology. Their wars drove military developments in East Asia and spread gunpowder technology westward. You’d think this statement would be uncontroversial. After all, the Mongols created the world’s largest empire, connecting East Asia to South Asia, Western Asia, the Middle East, and Eastern Europe. Mongol commanders excelled at incorporating foreign experts into their forces, and Chinese artisans of all kinds followed Mongol armies far from home. Yet oddly, experts disagree about the extent to which—or even whether—Mongols used gunpowder weapons in their warfare, and some deny them a role in the dissemination of the technology.
How can there be disagreement about such a fundamental question? One reason is that most historians have a poor understanding about what early gunpowder weapons were like and what they were used for—they expect to find gunpowder weapons blasting down stone walls, as cannons would eventually come to do in the West. As we’ve seen, that’s not how gunpowder weapons worked in this period. Even the iron bombs of the Jin—the most powerful gunpowder weapons yet invented—were used not to batter walls but to kill people or, at most, to help destroy wooden structures. Moreover, at the time of the Mongol Wars, the most common gunpowder weapon was still the gunpowder arrow, used primarily as an incendiary. There’s no shortage of accounts referring to blazing arrows and fiery orbs hurled by Mongol catapults, but historians have argued that these were not gunpowder weapons on the grounds that gunpowder weapons would have attracted much more attention.
Another problem is that the Mongols left few historical documents to posterity. Even the records left by the Mongols’ regime in China—the Yuan dynasty—are fragmentary, and China is a place that takes its history seriously. The official History of the Yuan Dynasty, compiled by scholars in China after the fall of the Yuan in 1368, is sloppy and patchy compared to other official histories in the Chinese canon, and Sinologists have noted that Yuan documents are particularly reticent about military details. Scholars must piece together Mongols’ history from the sources of their beleaguered enemies, whose records tended not to survive burning cities. So although we can paint a fairly clear picture of the development of firearms technology during the Song-Jin Wars, our understanding of the more intense and catalytic Mongol Wars is less complete.
Even so, there seems to be little doubt that the Mongols were proficient in gunpowder weapons. No one fighting in the Chinese context—and the Mongols met their most determined resistance in the Chinese realm—could remain unconvinced about the power of gunpowder, which by the early 1200s had come to play an essential role in warfare.
Indeed, the Mongols had a chance to learn about gunpowder weapons from the masters of their use, the Jin dynasty.
The Mongol-Jin Wars
Genghis Khan launched his first concerted invasion of the Jin in 1211, and it wasn’t long before the Mongols were deploying gunpowder weapons themselves, for example in 1232, when they besieged the Jin capital of Kaifeng. By this point they understood that sieges required careful preparation, and they built a hundred kilometers of stockades around the city, stout and elaborate ones, equipped with watchtowers, trenches, and guardhouses, forcing Chinese captives—men, women, and children—to haul supplies and fill in moats. Then they began launching gunpowder bombs. Jin scholar Liu Qi recalled in a mournful memoir, how “the attack against the city walls grew increasingly intense, and bombs rained down as [the enemy] advanced.”
The Jin responded in kind. “From within the walls,” Liu Qi writes, “the defenders responded with a gunpowder bomb called the heaven-shaking-thunder bomb. Whenever the [Mongol] troops encountered one, several men at a time would be turned into ashes.” The official Jin History contains a clear description of the weapon: “The heaven-shaking-thunder bomb is an iron vessel filled with gunpowder. When lighted with fire and shot off, it goes off like a crash of thunder that can be heard for a hundred li [thirty miles], burning an expanse of land more than half a mu, a mu is a sixth of an acre], and the fire can even penetrate iron armor.” Three centuries later, a Ming official named He Mengchun ( 1474–1536) found an old cache of them in the Xi’an area: “When I went on official business to Shaanxi Province, I saw on top of Xi’an’s city walls an old stockpile of iron bombs. They were called ‘heaven-shaking-thunder’ bombs, and they were like an enclosed rice bowl with a hole at the top, just big enough to put your finger in. The troops said they hadn’t been used for a very long time.” Possibly he saw the bombs in action, because he wrote, “When the powder goes off, the bomb rips open, and the iron pieces fly in all directions. That is how it is able to kill people and horses from far away.”
Heaven-shaking-thunder bombs seem to have first appeared in 1231 (the year before the Mongol Siege of Kaifeng) when a Jin general had used them to destroy a Mongol warship. But it was during the Siege of Kaifeng of 1232 that they saw their most intense use. The Mongols tried to protect themselves by constructing elaborate screens of thick leather, which they used to cover workers who were undermining the city walls. In this way the workers managed to get right up to the walls, where they began excavating protective niches. Jin defenders found this exceedingly worrisome, so according to the official Jin History they “took iron cords and attached them to heaven-shaking-thunder bombs. The bombs were lowered down the walls, and when they reached the place where the miners were working, the [bombs were set off] and the excavators and their leather screens were together blown up, obliterated without a trace.”
The Jin defenders also deployed other gunpowder weapons, including a new and improved version of the fire lance, called the flying fire lance. This version seems to have been more effective than the one used by Chen Gui a century before. The official Jin History contains an unusually detailed description:
To make the lance, use chi-huang paper, sixteen layers of it for the tube, and make it a bit longer than two feet. Stuff it with willow charcoal, iron fragments, magnet ends, sulfur, white arsenic [probably an error that should mean saltpeter], and other ingredients, and put a fuse to the end. Each troop has hanging on him a little iron pot to keep fire [probably hot coals], and when it’s time to do battle, the flames shoot out the front of the lance more than ten feet, and when the gunpowder is depleted, the tube isn’t destroyed.
When wielded and set alight, it was fearsome weapon: “no one dared go near.” Apparently Mongol soldiers, although disdainful of most Jin weapons, greatly feared the flying fire lance and the heaven-shaking-thunder bomb.
Kaifeng held out for a year, during which hundreds of thousands died of starvation, but ultimately it capitulated. The Jin emperor fled. Many hoped the Jin might reconstitute the dynasty elsewhere, and here and there Jin troops still scored successes, as when a Jin commander led four hundred fifty fire lance troops against a Mongol encampment: “They couldn’t stand up against this and were completely routed, and three thousand five hundred were drowned.” But these isolated victories couldn’t break Mongol momentum, especially after the Jin emperor committed suicide in 1234. Although some Jin troops—many of them Chinese—continued to resist (one loyalist gathered all the metal that could be found in the city he was defending, even gold and silver, and made explosive shells to lob against the Mongols), the Jin were finished. The Mongols had conquered two of the three great states of the Song Warring States Period, the Xi Xia and the Jin. Now they turned to the Song.
The Song-Mongol Wars
It’s striking that the Song, this supposedly weak dynasty, held the Mongols off for forty-five years. As an eminent Sinologist wrote more than sixty years ago, “unquestionably in the Chinese the Mongols encountered more stubborn opposition and better defense than any of their other opponents in Europe and Asia.”
Gunpowder weapons were central to the fighting. In 1237, for example, a Mongol army attacked the Song city of Anfeng, “using gunpowder bombs [huo pao] to burn the [defensive] towers.” (Anfeng is modern-day Shouxian, in Anhui Province.) “Several hundred men hurled one bomb, and if it hit the tower it would immediately smash it to pieces.” The Song defending commander, Du Gao, fought back resourcefully, rebuilding towers, equipping his archers with special small arrows to shoot through the eye slits of Mongol’s thick armor (normal arrows were too thick), and, most important, deploying powerful gunpowder weapons, such as a bomb called the “Elipao,” named after a famous local pear. He prevailed. The Mongols withdrew, suffering heavy casualties.
Gunpowder technology evolved quickly, and although sources are sketchy, scattered references to arsenals show that gunpowder weapons were considered central to the war effort. For example, in 1257, a Song official named Li Zengbo was ordered to inspect border cities’ arsenals. He believed that a city should have several hundred thousand iron bombshells, and a good production facility should produce at least a couple thousand a month. But his tour was disheartening. He wrote that in one arsenal he found “no more than 85 iron bomb-shells, large and small, 95 fire-arrows, and 105 fire-lances. This is not sufficient for a mere hundred men, let alone a thousand, to use against an attack by the … barbarians. The government supposedly wants to make preparations for the defense of its fortified cities, and to furnish them with military supplies against the enemy (yet this is all they give us). What chilling indifference!”
Fortunately, the Mongol advance paused after the great khan died in 1259. When it resumed in 1268, fighting was extremely intense, and gunpowder weapons played significant roles. Blocking the Mongols’ advance were the twin fortress cities of Xiangyang and Fancheng, which guarded the passage southward to the Yangze River. The Mongol investment of these cities was one of the longest sieges of world history, lasting from 1268 to 1273. The details are too numerous to examine here, but two episodes are salient, each of which involved a pair of heroes.
The first was a bold relief mission carried out by the so-called Two Zhangs. For the first three years of the siege, the Song had been able to receive food, clothing, and reinforcements by water, but in late 1271 the Mongols had tightened their blockade, and the inhabitants had become desperate. Two men surnamed Zhang determined to run the blockade and take supplies to the cities. With a hundred paddle wheel boats they traveled toward the twin cities, moving by night when possible, red lanterns helping them recognize each other in the darkness. But a commander on the Mongol side learned about their plans and prepared a trap. As they approached the cities they found his “vessels spread out, filling the entire surface of the river, and there was no gap for them to enter.” Thick iron chains stretched across the water.
According to the official Song History, the two Zhangs had armed their boats with “fire-lances, fire-bombs, glowing charcoal, huge axes, and powerful crossbows.” Their flotilla opened fire, and, according to a source recorded from the Mongol side, “bomb-shells were hurled with great noise and loud reports.”30 Wang Zhaochun suggests that the fire bombs used on the two Zhangs’ boats were not hurled by catapults but were shot off like rockets, using the fiery coals the vessels carried. This would be exciting, but unfortunately the evidence is inconclusive. Historian Stephen Haw suggests that the vessels carried guns, which is also possible, but again the evidence is inconclusive.
In any case, the fight was brutal and long. The Zhangs’ soldiers had been told that “this voyage promises only death,” and many indeed died as they tried to cut through chains, pull up stakes, hurl bombs. A source from the Mongol side notes that “on their ships they were up to the ankles in blood.” But around dawn, the Zhangs’ vessels made it to the city walls. The citizens “leapt up a hundred times in joy.” When the men from the boats were mustered on shore, one Zhang was missing. His fate remains a mystery. The official Yuan History says one Zhang was captured alive. The official Song History has a more interesting story. A few days after the battle, it says, “a corpse came floating upstream, covered in armor and gripping a bow-and-arrow.… It was Zhang Shun, his body pierced by four lances and six arrows. The expression of anger [on his face] was so vigorous it was as though he were still alive. The troops were surprised and thought it miraculous, and they made a grave and prepared the body for burial, erected a temple, and made sacrifices.” Other sources suggest that Zhang Shun was indeed killed in battle. He was later immortalized in the famous novel The Water Margin.
Alas, the supplies didn’t save Xiangyang, because the Mongols had a pair of heroes of their own. Two Muslim artillery specialists—one from Persia and one from Syria—helped construct counterweight trebuchets whose advanced design allowed larger missiles to be hurled farther. They came to be known in China as “Muslim catapults” or “Xiangyang catapults,” and they were devastating. As one account notes, “when the machinery went off the noise shook heaven and earth; every thing that [the missile] hit was broken and destroyed.” Xiangyang’s tall drum tower, for example, was destroyed in one thundering crash. Did these trebuchets hurl explosive shells? There’s no conclusive evidence, but it would be surprising if they didn’t, since, as we’ve seen, bombs hurled by catapults had been a core component of siege warfare for a century or more. In any case, Xiangyang surrendered in 1273.
The Mongols moved south. A famous Mongol general named Bayan led the campaign, commanding an army of two hundred thousand, most of whom were Chinese. It was probably the largest army the Mongols had commanded, and gunpowder weapons were key arms. In the 1274 Siege of Shayang, for example, Bayan, having failed to storm the walls, waited for the wind to blow from the north and then ordered his artillerists to attack with molten metal bombs. With each strike, “the buildings were burned up and the smoke and flames rose up to heaven. What kind of bomb was this? The sources on the Battle of Shayang don’t provide details, but earlier references suggest that it was a type of gunpowder bomb. A reference to it appears in an account of a battle of 1129, when Song general Li Yanxian was defending a strategic pass against Jin troops. At one point, the Jin attacked the walls day and night with all manner of siege carts, fire carts, sky bridges, and so on, and General Li “resisted at each occasion, and also used molten metal bombs. Wherever the gunpowder touched, everything would disintegrate without a trace.” The molten metal bomb was a probably a catapult projectile that contained gunpowder and molten metal, a frightening combination. It didn’t work for General Li in 1129: he lost the battle and either committed suicide or was killed, depending on which account you believe, but it did work for Bayan in 1274. He captured Shayang and massacred the inhabitants.
Gunpowder bombs were also present at a more famous Mongol massacre, the Siege of Changzhou of 1275, the last major battle of the Mongol-Song Wars.46 Bayan arrived there with his army and informed the inhabitants that “if you … resist us … we shall drain your carcasses of blood and use them for pillows.” His warnings were ignored. His troops bombarded the town day and night with fire bombs and then stormed the walls and began slaughtering people. Perhaps a quarter million were killed. Did his troops get new pillows? Sources don’t say, but it seems that a huge earthen mound filled with dead bodies lasted for centuries. Bones from the massacre were still being discovered into the twentieth century.
The Song held out for another four years, often with mortal bravery, sometimes even blowing themselves up to avoid capture, as when, in 1276, a Song garrison managed to hold the city of Jingjiang in Guangxi Province against a much larger Mongol force for three months before the enemy stormed the walls. Two hundred fifty defenders held a redoubt until it was hopeless and then, instead of surrendering, set off a huge iron bomb. According to the official Song History, “the noise was like a tremendous thunderclap, shaking the walls and ground, and the smoke filled up the heavens outside. Many of troops [outside] were startled to death. When the fire was extinguished they went in to see. There were just ashes, not a trace left.”
Bombs like this one were the most significant gunpowder weapons in the Song-Mongol Wars, but in retrospect the most important development was the birth of the gun.
What is a gun? The efficiency of a projectile-propelling firearm is directly related to how much of the expanding gas from the gunpowder reaction can get past the projectile. The technical term is “windage,” and less windage means more energy imparted to the projectile. A true gun therefore has a bullet that fits the barrel. During the Jin-Song Wars, fire lances were loaded with bits of shrapnel, such as ceramics and iron. Since they didn’t occlude the barrel, Joseph Needham calls them “coviatives”: they were simply swept along in the discharge. Although they could do damage, their accuracy, range, and power were relatively low.
In the late 1100s and the 1200s, the fire lance proliferated into a baffling array of weapons that spewed sparks and flames and ceramics and anything else people thought to put in them. This Cambrian Explosion of forms is similar to that found in the early gunpowder period itself—the fire birds, rolling rocket logs, and so on—and a famous military manual known as the Book of the Fire Dragon, compiled in the Ming period but partially written in the late 1200s, describes and illustrates many of these weapons, which historians have called, as a general category, “eruptors.”
These eruptors had fantastic names. The “filling-the-sky erupting tube” spewed out poisonous gas and fragments of porcelain. The “orifice-penetrating flying sand magic mist tube” spewed forth sand and poisonous chemicals, apparently into orifices. The “phalanx-charging fire gourd” shot out lead pellets and laid waste to enemy battle formations. We find these and other weapons jumbled together in the Book of the Fire Dragon, which makes it difficult to determine when they emerged and how they were used. But unfortunately, we must use whatever sources we can find, because starting in the Song-Mongol Wars, our documentary record becomes sparse, and it remains so through the Mongol period that followed, whose leaders, as I’ve noted, left unusually poor documentation relative to other Chinese dynasties.
It is clear that fire lances became common during the Mongol-Song Wars. In 1257, a production report for an arsenal in Jiankang Prefecture refers to the manufacture of 333 “fire-emitting tubes”, and two years later the Song History refers to the production of something quite similar, a “fire-emitting lance”, which emitted more than just fire: “It is made from a large bamboo tube, and inside is stuffed a pellet wad. Once the fire goes off it completely spews the rear pellet wad forth, and the sound is like a bomb that can be heard for five hundred or more paces.” Some consider this “pellet wad” to be the first true bullet in recorded history, because although the pellets themselves probably did not occlude the barrel, the wad did.
Yet a truly effective gun must be made of something stronger than bamboo. Traditionally, historians have argued that metal guns emerged after the Mongols defeated the Song and founded the Yuan dynasty in 1279. Researcher Liu Xu, for instance, writes, “It was the Yuan who completed the transition from the bamboo- (or wood- or paper-) barreled firearm to the metal-barreled firearm, and the first firearms in history appeared in China in the very earliest part of the Yuan.” Similarly, other scholars, including Joseph Needham, have suggested a date of around 1280.
Archaeological evidence tends to corroborate this view. Take, for instance, the Xanadu gun, so named because it was found in the ruins of Xanadu, the Mongol summer palace in Inner Mongolia. It is at present the oldest extant gun whose dating is unequivocal, corresponding to 1298. Like all early guns, it is small: just over six kilograms, thirty-five centimeters long. Archaeological context and the straightforward inscription leave little room for controversy about the dating, but it was certainly not the first of its kind. The inscription includes a serial number and other manufacturing information that together indicate that gun manufacture had already been codified and systematized by the time of its fabrication. Moreover, the gun has axial holes at the back that scholars have suggested served to affix it to a mount, allowing it to be elevated or lowered easily for aiming purposes. This, too, suggests that this gun was the product of considerable prior experimentation.
The Xanadu gun is the earliest dated gun, but undated finds may predate it. One famous candidate is a piece discovered in 1970 in the province of Heilongjiang, in northeastern China. Historians believe, based on contextual evidence, that it is from around 1288. One careful analysis argues persuasively that it was likely used by Yuan forces to quash a rebellion by a Mongol prince named Nayan. Like the Xanadu gun, it is small and light, three and a half kilograms, thirty-four centimeters, a bore of approximately two and a half centimeters.
Yet archaeologists in China have found evidence that may force us to move back the date of the first metal firearms. In 1980, a 108-kilogram bronze gun was discovered in a cellar in Gansu Province. There is no inscription, but contextual evidence suggests that it may be from the late Xi Xia period, from after 1214 but before the end of the Xi Xia in 1227 (Gansu was part of Xi Xia territory). What’s intriguing is that it was discovered with an iron ball and a tenth of a kilogram of gunpowder in it. The ball, about nine centimeters in diameter, is a bit smaller than the muzzle diameter of the gun (twelve centimeters), which indicates that it may have been a coviative rather than a true bullet-type projectile. In 1997, a bronze firearm of similar structure but much smaller size (just a kilogram and a half) was unearthed not far away, and the context of its discovery seems to suggest a similar date of origin. Both weapons seem more primitive than the Xanadu gun and other early Yuan guns, rougher in appearance, with uneven casting. Future archaeological discoveries will develop our understanding with greater certitude, but for now, it does seem possible that the earliest metal proto-guns were created in the late Xi Xia state, in the early 1200s.
Although historians debate the precise date of the gun’s origin, at present the disputes are in terms of decades. It seems likely that the gun was born during the 1200s and that the Mongols and their enemies aimed guns at each other. After defeating the Song dynasty in 1279 and founding the Yuan dynasty, the Mongols and their Chinese troops invaded Japan, Vietnam, Burma, and Java, wars that stimulated further innovation, although, alas, records are few and say little about gunpowder weapons.
Equally important, although the Yuan brought relative peace within the borders of the Middle Kingdom itself, it was not a lasting peace. As the Yuan dynasty dissolved during the early 1350s, guns played a central role in the bloody wars that followed. The most successful gunpowder lord was a poor monk named Zhu Yuanzhang, whose gunmen succeeded in establishing one of the most impressive dynasties in China’s history, the great Ming, which scholars now call the world’s first gunpowder empire.