The evolution of military architecture is to a large extent linked to the development of siege warfare. The emergence of new ideas and technologies within the field of siege warfare was often followed by changes in the method of fortification and the defense of strongholds. This sequence could be reversed: innovations in the field of military architecture encouraged the development of siege machines and sapping. In some cases a substantial period would elapse before a suitable architectural solution was found, since the conversion and upgrading of an “old” fortress to fit new methods of siege warfare was a complex and often expensive task.
The Mongolian army that prompted the strengthening and building of fortresses in the early decades of the Mamluk period did not resemble any of the contemporary Middle Eastern armies. Neither in size nor in structure could it be compared with the Ayyubid or the Frankish forces that fought in the Levant. Thus, the Mamluk fortifications built by Baybars and his successors should be studied in the light of Mongolian technology and methods of siege warfare.
The aim of this article is to provide an account of Mongolian siege warfare on the eve of Hülegü’s campaign to the west (1253). In addition, it will follow and examine developments in the field of siege warfare within the Īlkhānid state. Did the Mongols possess knowledge or technology that was not known amongst the Frankish, Ayyubid, Armenian and Mamluk armies?
The power of the Mongol army lay in its vast numbers of mounted archers, their swift and skilled maneuvers on the battlefield and their impressive ability to cover great distances in a way that very few contemporary armies were capable of matching. However, the military skills needed to conduct a successful siege were not found in the Mongol army that was gathered on the steppe by Chinggis Khan. Planning and building dams, ramps and siege-machines required engineers, carpenters and trained soldiers. Siege warfare demanded expertise and knowledge that were practically foreign to the nature of the Mongol army.
The following excerpt, taken from the Secret History of the Mongols refers to Ögedei (r. 1229–41). The Great Khan is enraged with his son, Güyük for the disrespect he had shown towards Batu during a feast in celebration of a successful campaign. It clearly displays Mongol opinion concerning the difficulties involved in siege warfare and the inferior status attributed to those who fought in sieges.
We [Ögedei] shall place him [Güyük] in the vanguard:
We shall make him climb the town walls
Which are as high as mountains
Until the nails of his ten fingers are worn away;
We shall place him in the garrison army
We shall make him climb the town walls
Which are made of hard-pounded earth
Until the nails of his five fingers are ground down.
Throughout the Mongol Empire’s existence and during the various stages of its army’s development, open battlefields were always favored over engaging an enemy fighting from strongholds and fortified cities. Embarking on a long siege could delay the army for a considerable length of time and disrupt a campaign that was carefully planned according to a strict schedule.5 Siege warfare forced the army to halt, to set up a camp that could serve them if necessary for an extended period and to procure sufficient pasture and water for thousands of horses and the large herds that were an integral part of Mongolian armies.
Chinggis Khan had quickly learnt and acknowledged the shortcomings of the Mongolian army and it was he who initiated the recruitment of foreign artisans. This became a ell-established policy among his successors. Craftsmen essential to the army’s campaigns were recruited from the lands that the Mongols conquered. The status, religion or origin of these people was of no significance to the Mongols, and their recruitment was determined only by their skill, knowledge and experience.
The need for siege units first arose when Chinggis Khan moved across the steppe into northern China (1211–1234) and faced the walled cities of the Chin Empire. From this time onwards siege units were to be regularly recruited among the conquered states of northern China, and were to serve the Mongol army until the late thirteenth century. In 1211 a Chinese officer by the name of Chang Pa-tu supervised the Mongol army’s siege machines. After him came Hsueh T’a-la-hai who commanded both the siege machines and the navy.
When Chinggis Khan invaded Central Asia he was said to have had with him ten thousand soldiers who could work the siege machine batteries. The recruitment of siege units among the Northern Chinese continued during the reign of the great Khan Möngke (r. 1253–9) who conscripted blacksmiths, carpenters and gunpowder-makers. Hülegü followed suit and in 1253 when the campaign to the west was being organized “he sent messengers to Cathay (North China) to bring a thousand households of Cathaian catapult men, naphtha throwers and crossbowmen.” During Qubilai Khan’s reign siege experts were still being recruited among the Northern Chinese and teams were brought from the region of the Huai River. Only in 1272 was this trend interrupted, when Qubilai turned to his nephew the Īlkhān Abagha and asked him to send two Muslim engineers who specialized in building siege engines. Thee years later he established a Muslim siege unit that included soldiers and artisans specializing in siege weapons of the type used in the Eastern Mediterranean.
From the year that Chinggis Khan began to besiege the cities of Northern China and up to the time Hülegü set out on his campaign, the Mongols were constantly engaged in warfare. During those forty years the Mongol army besieged tens of strongholds and cities possessing larger, stronger and more advanced fortifications than those found in the Levant. Complex siege operations were carried out, some demanding the building of dams, the diversion of rivers and the raising of large earth ramparts. Apart from the necessary engineering knowledge, the scale of these operations required hundreds if not thousands of laborers. Prisoners taken from the local populations around the besieged city were often the source of manpower. One of the most detailed accounts of Mongolian methods of siege warfare is given by John of Plano Carpini, an emissary of Pope Innocent IV, who traveled in 1245–7 to the court of the Great Khan.
They [The Mongols] reduce fortresses in the following manner. If the position of the fortress allows it, they surround it, sometime even fencing it round so that no one can enter or leave. They make a strong attack with engines and arrows and they do not leave off fighting by day or night, so that those inside the fortress get no sleep; the Tartars however have some rest, for they divide up their forces and they take it in turns to fight so that they do not get too tired. If they cannot capture it in this way they throw Greek fire … If they are still unsuccessful and the city or fort has a river, they dam it or alter its course and submerge the fortress if possible. Should they not be able to do this, they undermine the city and armed men enter it from underground; once inside, some of them start fires to burn the fortress while the rest fight the inhabitants. If they are not able to conquer it even in this way, they establish a fort or fortification of their own facing the city, so as not to suffer any injury from the missiles of the enemy; and they stay for a long time over against the city, unless by chance it has outside help from an army which fights against the Tartars and removes them by force. While they are pitched before the fortification they speak enticing words to the inhabitants making them many promises to induce them to surrender into their hands.
Hülegü’s campaign to the west was the last of its kind under the united Mongol Empire. Although the source says that Hülegü recruited a thousand soldiers from northern China who specialized in siege warfare, it is not clear whether the Īlkhānid state established by the Mongols in 1260 maintained this custom and continued to recruit Northern Chinese siege experts. The exact size and composition of Hülegü’s army is not known, but it is worth looking at some of the figures and conclusions suggested by scholars who have studied Hülegü’s journey. None of the armies that joined Hülegü had their own siege units; it seems they were mainly made up of mounted archers. According to Martinez the armies that marched to the west under Hülegü’s command were similar to those that fought under Chinggis Khan. The size of Hülegü’s army has been estimated by a number of historians. According to Allsen the core of the army numbered seventy five thousand. A large Mongolian body, similar in size and composition, which had been in Asia Minor, Afghanistan and the west of the Caucausus, joined Hülegü before he entered the Middle East. Thus Hülegü had under his command roughly a hundred and eighty thousand soldiers. Both Smith and Allsen suggest that the army was considerably larger, eventually numbering three hundred thousand men, of whom only half were Mongolian. Smith estimated that from fifteen to seventeen tümens (a tümen roughly equals ten thousand men) were composed of both Mongolian and Turkish (Turikc) soldiers; to those he added contingents belonging to local vassals who were fully subordinated to the Mongols. The number oftümens composed of non-Mongols was, in Smith’s estimation, thirteen. We have no further information about possible siege units, other than the teams recruited by Hülegü on the eve of his campaign.
By the time Hülegü set out for the West, Mongol siege warfare had come to rely and depend heavily if not completely on the Northern Chinese contingents. In the four decades that elapsed between the death of Chinggis Khan and the reign of Möngke, the Mongolian Khans faithfully observed this policy of recruiting specialists in this particular field, and did not train their own men in the art of siege warfare.
Seeing that Hülegü besieged cities and fortresses in the Middle East by employing Chinese units and technology, a survey of the siege methods in use in northern China until the mid-thirteenth century is in order.
Chinese siege machines in the thirteenth century
The most common feature of Chinese siege machines during this period is the fact that they were propelled by manual power. As well as the type and design of the machines, their strength and efficiency depended on the size of the team that pulled the ropes. Their greatest drawback was the large number of people required to work them. While even simple siege machines needed forty men, the larger ones demanded a force of two hundred and fifty men. This obviously made the teams an easy target for the enemy.
Chinese siege machines can be divided into three main categories: catapults that fired round clay balls; siege machines that hurled inflammable materials; and large and powerful crossbows.
The Pao: the Chinese catapult
The word Pao (Phao), means literally to hurl or to throw. The Pao was mounted on a base that resembled a pyramid or a light cart, which made maneuvering it during a siege a slightly easier task. The type of wood used for the central arm was of great importance; in most cases it was either oak or black birch, soaked in water for at least six months. The length of the central beam varied between 5.58 and 7.75m. One end had a leather sling that held the catapult-stone and the other had ropes to pull on. A more advanced type of catapult machine had several beams and could hurl five or seven stones simultaneously. This latter type of siege machine does not appear to have been known among the Franks or the Mamluks. In addition, there were also siege machines where the beam was mounted on an axis, enabling the machine to be aimed in different directions without having to move the entire structure. Most siege machines were built on those basic lines. The main difference between the various types was in the length of the central beam and the number of beams. Those two components dictated the number of men needed to operate the machine and the weight of the stones that could be hurled. The next table lists the various types of siege machines and the number of men needed to operate them, the distance each machine could fire and the weight of the stone or clay projectiles.
A number of historical narratives concerning the Mongol invasion into the Middle East provide information that does not comply with the figures given in the above table. However, the figures proposed provide a reliable basis for estimating the force of Chinese siege machines. An interesting aspect of Chinese siege machines is the use of clay balls as projectiles. This was recommended by Ch’en Kuei (ca. ad 1130), author of the twelfth-century war manual Shou-ch’eng lu.
The counterweight siege machine first appeared in China during Qubilai’s reign (1260–94). We have no written evidence of the use of counterweight siege machines by the Īlkhānids other than an illustration in the manuscript of the Jāmī‘ al-tawārīkh (dated 1306–14) at the Edinburgh University Library. The most convincing evidence of the penetration of Islamic siege technology from Syria to the Īlkhānid state and further into the Chinese Empire is dated 1272. During Qubilai’s wars against the Song state he had sought the advice and help of his nephew, the Īlkhān Abagha, asking for two Muslim siege engineers to be sent to his court. This request indicates that siege technology in the Eastern Mediterranean was more advanced than that of the Īlkhānid state and of the Chinese siege units employed by Qubilai. We may also conclude that the Īlkhānid army had begun to use the counterweight trebuchet soon after the state was established. Two Muslim engineers who specialized in building siege machines were brought to Qubilai’s court in 1272. was from Mayyāfarīqin and from Aleppo. At the court they built what is known in the Mamluk sources as “the large Frankish manjanīq”; in China it received the title “the Muslim phao.”
A description of this siege machine is given in the Yuan-Shi. Its main advantages were that it did not require a large team; the projectiles were considerably heavier and could cover a greater distance. The eight of the stones could reach 90kg and more. According to the source, when they hit the ground they made craters that measured 2.17m in diameter. The sound toe through the sky and the earth and the damage was considerable. This appears to be the first Chinese description, if somewhat exaggerated, of the counterweight trebuchet.