In addition to stone and clay projectiles, vessels containing inflammable materials were a favorite type of ammunition in Chinese siege warfare. Certain siege machines had names such as “Hao Pao,” i.e. a fire-hurling siege machine. Pots with wicks of flax or cotton were used, containing a combination of sulphur, saltpeter (potassium nitrate), aconite, oil, resin, ground charcoal and wax. This recipe in fact contains all the basic ingredients for making gunpowder, but the emphasis in the recipe given above was on producing toxic fumes; it was called “tu-yao yen-ch’iu,” literally a ball of smoke and fire.
The frequent use of inflammable materials in Chinese siege warfare was most probably due to the fact that a large percentage of both public and private buildings were constructed of wood and bamboo. Even houses made of mud bricks had a wooden frame. In addition to clay roof tiles, thatched roofs could be found in both northern and southern China. The materials used for thatching included straw from wheat or rice, canes and various types of wild grass.
It is no wonder then that the main dread of the besieged was of fires inside the city. Pots containing inflammable materials were hurled into a densely populated city where many structures were of wood. Occasionally, even the city towers along the curtain walls were a combination of bricks and wood; this can be seen in illustrations of the city Shao Hsing dating to the thirteenth and fourteenth centuries. A few examples of wooden gate towers date to the fourteenth and sixteenth centuries. In some cases a high wooden palisade was erected parallel to the stone or brick curtain wall.
The immense destruction caused to the city of Bukhara when it was besieged by Chinggis Khan illustrates the effectiveness of inflammable materials in siege warfare.
He [Chinggis-Khan] now gave orders for all quarters of the town to be set on fire; and since the houses were built entirely of wood, within several days the greater part of the town had been consumed, with the exception of the Friday mosque and some of the palaces, which were built with baked bricks … mangonels were erected, bows bent and stones and arrows discharged … For days they fought in this manner.
In contrast to the widespread custom in large parts of China and some parts of Central Asia of building with wood and cane, in the Eastern Mediterranean public, private and military buildings were constructed mainly of stone. This was both plentiful and relatively cheap when compared to the price of wood. Although inflammable materials were used in siege warfare by the Ayyubids, the Franks and the Mamluks, their effect was considerably less disastrous.
At this point of the discussion we should note that the most common material for the construction of curtain walls in China and Central Asia was rammed earth sometimes faced with stone and/or sun-dried mud bricks. In contrast to Middle Eastern and European strongholds that were built on prominent sites (hills, mountains, cliffs and the like) “no such preference for an elevated, easily defensible site, however, seems to have nourished city site selection in China.” According to Di Cosmo, wall building was a military concept and a technology that originated on the Central Plain. Walls asserted the state’s political and military control over certain areas. “Like roads, walls provide the logistic infrastructure to facilitate communications and transportation, vital elements for armies employed in the occupation or invasion of foreign territory.” This function attributed to walls in China differs from their function in the Eastern Mediterranean. Chinese walls were not constructed only for military purposes. They are often located on a river bank and their first and at times most important task was to protect the population from floods. In certain areas in the northwest the walls acted as screens against sandstorms. Forbidding earthen ramparts almost became the trademark of Chinese fortifications, although certain sections such as the gates and towers were constructed of bricks or stone. Although they were effective their main fault was the large area of “dead space” below the wall. The straight lines and relatively few towers did not provide the defenders with sufficient flanking fire.
Was gunpowder brought over to the Middle East by the Mongols?
One of the most controversial and intriguing issues debated among a wide range of scholars is the arrival and development of gunpowder. The differences of opinion concerning the use and efficacy of gunpowder during the thirteenth century call for a short survey. The majority opinion is that gunpowder was used by Chinese armies in the mid thirteenth century and even earlier. This group includes the following scholars: Goodrich, Chia-Shêng, Allsen, Khan, Martin, Chase, DeVries and Needham. Needham has conducted the most extensive archaeological and historical research on the subject of the development of gunpowder and firearms in China, arguing that by the mid thirteenth century the Chinese could destroy city gates and walls using gunpowder. He cites the four sieges in which gunpowder was used: Kayfeng (1232), Merv, Samarqand, and probably also during the siege of Baghdad (1258). Martin, who carried out a thorough study of the Mongol army, holds a similar opinion. Khan, who surveyed the sources that cover the Mongol invasion of the Delhi sultanate, found sufficient evidence that gunpowder was used by the Mongol forces. Allsen also believes that gunpowder began to be utilized around the same time, but presents his opinion with some caution. Among the one thousand households Hülegü brought with him on his campaign to the west, he thinks there were men who knew how to produce gunpowder. Allsen says that at the battle near the Amu Darya (1220) the Mongol army fired rockets launched with the help of gunpowder. Like Needham, Allsen claims that during the siege of Baghdad the Mongols used some form of gunpowder. Many scholars rely to a great extent on the studies published by Needham. Franke and May are currently among the few who clearly state that even at the end of the Yuan Dynasty (1368) gunpowder was not a weapon that could determine the outcome of a battle. According to May “its use remains speculations.” Franke’s conclusions are based on a survey of the archaeological finds and the historical sources, all of which show that the number of casualties as a result of the use of gunpowder was very low. Ayalon demonstrated the problems of terminology in the Mamluk sources. His conclusion was that there is no definitive evidence that firearms were being used during the thirteenth and the first half of the fourteenth century, and that gunpowder was no more than an incendiary.
Returning to the question of whether the Northern Chinese contingents in Hülegü’s army employed gunpowder technology in siege warfare requires an examination of the three sources that give an account of his army on the eve of his journey west.
• Te earliest source was written by Malik Juwaynī, a Persian official who served the Mongols (d. 681/1283). The Ta’rīkh-i jahān-gushā (‘History of the world-conqueror’) is an encyclopedic history of Chinggis Khan and his times that documents the events till 1257.
• Te second source was written by the Persian historian Rashīd al-Dīn Allāh Abū ‘l-Khayr (d. 718/1318). TheJāmi‘ al-tawārīkh (‘Complete Collection of Histories’) is the first universal history and was compiled ca. 1310 (an earlier version was completed in 1306–7).55 It records the history of the Īlkhānid state established by Hülegü soon after the fall of Baghdad and the execution of the Abbasid Caliph (1258).
• Te latest source is the Yuanshi, a Chinese official history of the dynasty founded by the Mongols, compiled ca. 1370.
Neither Juwaynī nor Rashīd al-Dīn, both of whom describe Hülegü’s campaign, mention the use of gunpowder by the siege units of the Mongol army. It is perhaps possible that they were not familiar with this new weapon and described it by the terminology often used for the various incendiary weapons that were known among Middle Eastern armies. However, this does not seem to be the case. Both works contain only a short paragraph on the whole subject of the Northern Chinese siege units and neither notes anything unusual or new concerning the arsenal of Hülegü’s army. Thus it seems more than likely that Mongol methods and weapons did not appear strange or unknown in the field of siege warfare.
A close examination of the Persian and Chinese texts is important to fully understand the matter at hand. Juwaynī says that among the siege units there were soldiers specializing in hurling . The Persian term he uses is andāzān. Rashīd al-Dīn mentions these very same units and uses the same terminology to describe the men who hurl . In addition, he writes that among those siege units were teams he terms the charkh andāz. The Persian word charkh literally means “a round object,” while andāz means “to throw” or hurl. Rashīd al-Dīn is in fact referring to the teams operating the siege machines that hurled round catapult stones.
The Chinese source is more complex than the two Persian ones. The Yuanshi describes the recruitment of craftsmen/artisans for the siege warfare units in the armies of Chinggis Khan and Ögedei. In 1252 Hülegü’s siege units were summoned from the same source of manpower. The term used for a particular craftsman in Chinese is a combination of two words. The first describes the raw material utilized by a specific craft. The second isjiang which can be best translated as smith. The list in the Yuanshi includes blacksmiths who work with iron, smiths who work with wood, i.e. carpenters, and smiths who work with gold, i.e. goldsmiths. The last raw material mentioned in the list is huo – fire. In contrast to the first three combinations which use the word jiang, huo appears on its own. It is therefore difficult to translate and reach a definite conclusion concerning its exact meaning in this context. The term hou jiang does not appear at all in the Hanyu Dacidian (the Chinese 12-volume dictionary) or in the Ciyuan (a dictionary orientated towards classical Chinese). The term hou jiang appears once more in the Yuanshi and there too comes directly after a mention of goldsmiths. Further, the combination hou jiang never seems to appear in any of the other earlier or later official Chinese histories such as the Mingshi, Jinshi, or Songshi. It is therefore difficult to conclude that the Mongols used gunpowder in siege warfare or to assume that they had men in their siege units who knew how to produce gunpowder. The fact that the Persian sources are silent and do not mention a dramatic debut of a new technology brought by the Mongols, as well as the fact that they simply stick to terms that were well-known in descriptions of siege warfare in Persian texts, further supports the view that gunpowder did not arrive in the Middle East with Hülegü’s Mongol army.
Chuang zi nu: the giant crossbow
The chuang zi nu was one of the most dominant siege weapons in the Mongolian army during this period. Its construction and operation were complicated and among the Chinese experts recruited by Hülegü were men skilled in the assembly and operation of those giant bows.
The structure of this siege machine was similar to that of the crossbow carried by infantry archers. The word chuang zi nu means literally “a giant crossbow shaped like a bed.” It was made by using one, two or three giant crossbows connected to each other and mounted on a cart so that the machine could be maneuvered with ease. The crossbows were constructed from wood and bone, giving them flexibility and strength. The cod was drawn with a winch and the arrows were similar in size to spears and more than one arrow could be fired each time.
A bow of this type was used during Hülegü’s siege of the Assassins’ fortress at Maymundiz. Apart from arrows the size of spears, it fired burning torches that according to Juwaynī caused many casualties.
Many parallels can be drawn between the various types of siege machines used in the Middle East and in Northern China. Thee are however a number of important differences, the main one being that all siege machines in China were propelled by manpower. The Middle East had clearly made an advance, and besides the manually operated siege machines, it was using the counterweight trebuchet, which was more powerful and capable of firing heavier stone projectiles to a greater distance. It also required a considerably smaller team. The ropes pulled by men were replaced by a set of pulleys and a wooden box filled with stones that acted as a weight. The disadvantages of this new siege technology were that its size and weight meant it could not be maneuvered with ease, not even along short distances, and it had to be built and assembled by a professional team of carpenters and engineers. The Chinese on the other hand had the multiple armed siege machines that were not known to the armies of the Middle East even after their encounter with the Mongol army. The size and firepower of those siege machines must have been impressive if one takes into account that each machine could fire between five and seven stones at a time. Thee is also a great difference in the type of projectiles used, since clay catapult balls were unheard of amongst Franks, Ayyubids and Mamluks. Taking into account that a team of forty was needed for the operation of the smallest Chinese siege machine, this may explain the great number of a thousand skilled men that Hülegü recruited from Northern China for his siege units.
The use of incendiaries was common to both Middle Eastern and Northern Chinese armies, though it seems that they were more effective in Chinese and Central Asian warfare since wood, cane, and thatched roofs, all highly inflammable, were widespread building materials. The clay pots known as have been found in a number of archaeological sites on land and at sea though they were more successful in naval warfare where wooden ships and sails could easily catch fire.
Apart from the differences in siege machines employed by the armies, there was a vast difference in the way the Northern Chinese siege units in the Mongol army utilized the topography and natural surroundings of the area round a besieged city. This is one of the most impressive characteristics of siege warfare under the Mongol commanders.
Rivers were diverted, dams built and mud ramparts or brick walls were constructed in order to seal the city and cut it off from its surroundings. These large earthen works show an outstanding degree of thought and initiative on the part of well-trained engineering teams and skilled craftsmen, capable of planning and operating such large-scale projects. The rankish, Ayyubid and Mamluk siege teams dug sapping tunnels and worked a variety of different siege machines, but they never attempted to change the course of rivers and/or the area near the besieged city. The main reason was lack of human resources: without a huge labor force such ideas could not be carried out.
There can be no doubt that Eastern Mediterranean siege machines were more advanced. The counterweight trebuchet could hurl stones that weighed 95kg and more to a distance of 300m. On the other hand, the strength of the siege units employed by the Mongols apparently did not depend on superior siege technology or on changing the topography round the besieged city or fortress, but lay rather in the ability to recruit and position mass numbers of siege machines and teams that could run the entire siege operation day and night without halting. The siege of Nishapur (1221) is a good example. The force sent to besiege the city numbered 10,000 men under the command of Toghachar, a son-in-law of Chinggis Khan. The garrison was assisted by the entire population. Juvaini mentions mangonels, naphtha and crossbows used by the defenders. The city’s defense held for six months. It was only when Tolui arrived in April of 1221 with a significantly larger force that Nishapur was taken. The walls ere breached within three days.
Juwaynī describes the effort Tolui’s teams put into gathering stones for the siege machines: “although Nishapur is in a stony region they loaded stones at a distance of several stages and brought them with them. These they piled up in heaps like a harvest, and not a tenth part of them were used.” D’Ohsson and Martin describe the siege machines at Nishapur, giving exact numbers. The Mongols placed 3,000 giant crossbows, 300 stone-hurling siege machines, 700 machines that hurled pots of, 4,000 ladders and 2,500 piles of stones brought from the nearby mountains. The assault continued day and night. Assuming this source is reliable, even if the figures are exaggerated they give an idea of the immense strength of the siege contingents that fought in the service of the Mongol armies.
The source of manpower available to the Īlkhānid state differed from that of the Mongol empire. It is rather doubtful that Hülegü’s heirs continued to recruit men from Northern China for their siege contingents. This raises a number of questions concerning the composition, number and origin of the men in the Īlkhānid siege units. The chroniclers provide very little information. On the strength of previous Mongol policy it is more than likely that Muslim engineers were recruited and local siege technology was used along with that brought over from Northern China. But any assumption is bound to remain so for lack of firm evidence. However, it is possible to overcome this obstacle by analyzing the sieges conducted under Hülegü’s command and comparing them to those carried out in later years by his successors. This may enable us to draw some conclusions concerning the development and changes of siege warfare that occurred in the Īlkhānid army.