Reasons for Mongol Withdrawal
Many reasons are listed for the Mongol withdrawal from Hungary-Croatia and Europe in general. One that is common for most of them is that they present Mongol military power as unbeatable by Europeans, and rely solely on environmental (geographical, climatological) explanations for the Mongol withdrawal. In fact, most accounts present the Mongol withdrawal as having saved Europe, yet give no explanations as to how and why the Mongols withdrew. In general, however, there are four major theories which explain the Mongol withdrawal.
First theory, and also the most common one, is the political theory. According to this, Batu Khan withdrew upon receiving news of Ogodei Khan’s death in Mongolia (Ogodei died in December 1241., Batu will have received news in March 1242.). Upon receiving news, Batu Khan immediately ceased the campaign. Second is the ecological theory, which holds that the plains of Hungary simply did not have forage sufficient for Mongol horses, and thus that Europe in general was unsuitable for conquest, which Mongols recognized and thus retreated. Third is the limited goals theory, stating that Mongols intended only a limited expedition – either an exploratory raid or else a punitive expedition against Bela IV for harbouring Cumans. Fourth is the theory of military weakness, stating that Mongols had been so weakened by subjugating Eastern Europe that they could not continue further westwards.
The Political Theory
The political theory is the most popular one for the Mongol withdrawal. Mongols were in position to, after having shattered unified resistence in Poland and Hungary, push further West in 1242. Yet they terminated the campaign three months after khan’s death. This is supported by statements by Carpini, an emissary to the Mongol court, who states that the Mongols had planned to fight for 30 years, but had to retreat as the khan was poisoned. His statements are the only ones in any primary source that attribute the withdrawal to khan’s death.
Secondary literature notes that lack of clear laws of succession meant that the Mongol state was in danger of collapse whenever a new khan was being chosen. But the main reason why it finds such a widespread support is the preconception about the Mongol military might, which thus eliminates any military reasons as the cause of withdrawal.
Problems with the political theory however are many. First is that Carpini is not a reliable source on the matter. While he was not trying to mislead the readers of his report, he was wholly dependant on Mongols for much if not most of his information – all of the things he could not personally observe. He himself observed that Mongols held people from other nations in contempt, and while honest to one another, were extremely deceptive towards the foreigners. Therefore, anything that is based on Mongol sources – which is likely where Carpini received his information – has to be doubted. Carpini also provides inaccurate facts on the events surrounding Ogodei’s death (he was not poisoned, least of all by his son’s mistress, and it was Tolui’s widow’s sister and her son who were cupbearers for Ogodei), and thus his accuracy on other events must be doubted.
Rashid al-Din, a high-level minister of Ilkhanate, is overall a much more reliable source. He reports accurately on the events surrounding Ogodei, and thus he is a much better choice when discussing Mongol withdrawal from Europe. Rashid al-Din states that Mongol forces were unaware of the khan’s death when decision was reached to withdraw from Central Europe. He specifically states that the news of khan’s death had not yet reached the Mongol army when decision was made to withdraw from Croatia and Hungary in late March. And unlike Carpini, al-Din actually had access to internal documents of the Mongol Empire, as ortography of names makes it certain he was using Mongol sources – and these clearly state that withdrawing Mongols were unaware of khan’s death.
Rashid al-Din’s accounts of the movements of the Mongol army also show that Mongols were not exactly in a hurry to get home, or were aware they were needed there. In 1242., they attacked Cuman rebels, pursuing them all the way to Caucasus and spending a year in that region. The army only arrived to Volga at the end of 1243. The army, loaded with booty and animals, marched very slowly – combing the forests for rebels in the process. Neither does Rogerius mention any rumours of khan’s death as the column left Hungary. Batu also sent two of his subordinates northwards into Russian territory in search of Danilo of Galicia in late 1242. or early 1243. Overall, main goal of the Mongol army appears to have been consolidation of pre-1241. Conquests, rather than any haste to take part in a khuriltai.

In fact, the calls for khuriltai were not made until 1243. Guyug was still making his return to Mongolia when he heard of Ogodei’s death. He hurried back to Mongolia where his mother, Torogene, subsequently contravened the yasa and took the role of the regent. Only then were the messangers dispatched to summon the princes to a khuriltai. And yet, when Batu received the summons, he refused to go, claiming that his gout made travel impossible. Rashu al-Din clearly states such reasons were nothing but an excuse. Batu in fact never went to Mongolia after his invasion of Europe, and his repeated refusals to return delayed the khuriltai until 1246. In any case, it was impossible for Mongol couriers to make the trip in three months between Ogodei’s death and the beginning of withdrawal. Carpini’s party, using Mongol horses and Mongol guides, took five months to cover the distance between Kiev and Mongolia. William of Rubrick required four months, travelling from morning until night and changing horses two or three times per day. This also depended a lot on time of the year. Carpini’s return journey from Mongolia to Volga in middle of winter took from November 7th to May 9th, while Rubrick – travelling in summer – made this trip in two months. But couriers bringing news of Ogodei’s death will have been dispatched from Karakorum in the severest months of winter. Carpini’s and Rubrick’s accounts also make clear the lack of yam stations in Mongolia proper, unlike China where Mongols had inherited the very developed Chinese system. Thus, two and a half month trip is not likely.
Another problem with the political argument is that, if true, it would have made Europe a fairly unique theatre. Mongol campaigns in other areas continued to be waged immediately after Ogodei’s death and during the interregnum (1241 – 1246). Mongols were launching a campaign against multiple Song cities south of the Huai river in the autumn of 1242., and there was another campaign in 1245. while the throne was still unoccupied. And despite the death of Chomarkan in Caucausus in late 1241., Baiju replaced him and promptly invaded Asia Minor, crushing Seljuks at Kosedagh in 1243. and reducing them to a tributary state. Thus, it is impossible to find a reason why Mongols would have had to “take a break” in European theatre while continuing their conquests elsewhere. There was no cessation of campaigns because a khan had died. However, there is something important to note there: an army under Yasa’ur advanced into Syria in 1244., demanding submission of various Ayyubid rulers as well as the Bohemond V of Antioch. Bohemond V refused to dismantle his fortifications, and Yasa’ur’s army retreated from the region without attempting any sieges.
Nor is there proof that Batu had to retreat to secure himself against Guyug. First, in 1242., there was no reason to expect Guyug to be elected khan. Ogodei had wanted his grandson, Shiremun, to succeed him, and had raised Shiremun personally. It was only through Toregene’s machinations that Guyug had won. Second, there is no evidence that Batu had expected a civil war. He did send many of his brothers to Mongolia, and Subetei was permitted to return to great khan’s service. Batu himself submitted to new khan’s authority, carrying out a census, on khan’s orders, in 1247. Guyug’s march westward was likewise aimed at Middle East. Batu also went without complaint to meet the khan in Xinjiang in 1248., which does not make sense if he was hostile to the khan or had believed khan hostile to himself. Thus, Guyug’s death did not avert a civil war, because there was no civil war waiting to begin.
Overall, there are no political reasons that sufficiently explain Mongol withdrawal from Europe.
The Ecological Theory
The ecological theory emerged in 1972 with Denis Sinor’s article “Horse and Pasture in Inner Asian History” as an alternative to the political theory. Sinor, aware of the above issues with the political theory, argues that insufficiency of pasturage caused Mongols’ sudden evacuation of Hungary. He calculates that if a single horse required 120 acres of pasturage per year in pre-modern conditions, then the Nagy Alföld of Hungary could support a herd of 205 920 horses. At best, this would allow a force of 10 000 – 30 000 Mongols to occupy Hungary in realistic conditions, or a force of 68 000 in ideal conditions (each Mongol warrior had 3 – 5 horses). The Carpathian Basin simply could not support more, a fact which forced the Magyars to eventually adopt the sedantary lifestyle of their neighbours. Mongols thus could not sustain a campaign in Hungary, and moreover, never launched another one.
The main problem is that there is little support in the primary sources for this theory. Primary support lies in Thomas of Split, who had noted that Kada only took a fraction of his force when he approached the Adriatic coast because “there was not sufficient fodder for all the horses in the army; for it was the beginning of March, and the weather was still harshly cold.”. Yet this is specifically in reference to Coastal Croatia, whose very mountainous terrain is a far cry from the plains of Pannonia. Further, while terrain may have limited the size of the force, it is not certain it caused their retreat: Thomas notes that Tatars had remained in the Coastal Croatia for the whole of March, rather than passing through. Second element Sinor posits as supporting his theory lies in the famine which had occured after the Mongol invasion, yet it is clear from the accounts that the main reason for the famine was that the peasants had failed to either plant the crops or take in the previous year’s harvest due to Mongol invasion. Mongols themselves had destroyed much, and taken nearly all the animals so that the farmers were forced to harness themselves to plought the soil. Famine was, in fact, one of chief weapons that Mongols used in their efforts to crush resistance, and spells of famine were noted in all areas that Mongols had invaded. By contrast, Hungary had not suffered famine even during the Little Ice Age, and therefore climatic and environmental explanations for the famine are unsatisfactory. If anything, unusual cold of the winter of 1241/42 helped the Mongols, allowing them to cross the now frozen Danube.

Contemporary sources were also quick to notice when the environment wrought its effects on the Mongols and their herds. Juvaini notes that vast numbers of dignitaries assembled for Güyüg’s enthronement in 1246 caused food shortages and no fodder was left for the animals. The Yuanshi records drought on Mongolian steppe in 1248, which caused the drying up of rivers, enormous grass fires, and the deaths of 80 or 90 percent of cattle and horses, causing large numbers of Mongols to migrate to neighbouring areas. The Galician-Volynian Chronicle refers to “all the horses, cattle and sheep” of the Golden Horde Mongols dying in about 1287. Rubruck, during his time at Möngke’s court, observed a disastrous cold snap which killed innumerable livestock. Sources also note how Mongols responded to the environment, e.g. by migrating southwards when the snow grew too deep for grazing. During the second invasion of Hungary in 1285., the Galician-Volynian Chronicle records “a great famine” that killed thousands of Mongols (it should be noted that this great famine was likely a consequence of Hungarian castle warfare strategy, as opposed to solely environmental factors, but the 1285 invasion is a topic for another time). When it comes to 1241 invasion however, there is only a mention of famine following the invasion, but no mention of either a famine or food shortage affecting the Mongol army. In fact, the Mongols ended up leaving in spring, precisely when grass was first sprouting and a nomadic army would feel the least pressure to evacuate the area. Contemporaries writing the invasion specifically note that the famine was a consequence of the invasion and the destruction wrought by the Mongols, and therefore could not have caused their withdrawal. Invasion had forced the peasants to abandon the fields for two seasons, being unable to harvest the crops in autumn of 1241. or to sow them in the spring of 1242.
Bela IV himself had no idea that his country is, apparently, unsuitable for the occupation by a massive Mongol army. In fact, he believed the opposite. Writing to the pope in 1250., reporting the rumours about another Mongol invasion, Bela IV wrote “If … [Hungary] should fall into the possession of the Tartars, the gate to other lands of the Catholic faith would lie open. For one, because there is no ocean to hinder their approach to the Christians, and moreover, because it is exactly here that they are able to settle their enormous hosts better than elsewhere.”. While it might be possible to dismiss these claims as fear-mongering intended to raise a response by the Western Europe, there is no reason to believe that Pope would not have been able to spot a lie if it had been, in fact, a lie. Bela IV also made a point that Atilla had used Hungary as his base in the past, a fact that will have been known to all leaders of Europe. Mongols themselves agreed with Bela’s assessment. In 1254 Batu demanded a marriage alliance and Bela’s troops for use on a campaign into Western Europe. His successor Berke demanded that Hungary provide a quarter of its army for a planned drive into Europe. In exchange, it would receive exemption from tribute and even a fifth of the plunder. Bela answered none of these ultimatums. Guyug “raised the standard” to proceed against the Holy Roman Empire and all the Christian kingdoms in the West, and in 1260. Berke sent an embassy to Paris, threatening France with invasion if Louis IX refused to submit. Apparently, nobody had considered Mongol invasion of Europe an ecological and logistical impossibility.
And Mongols themselves had, in fact, conquered many areas unsuitable for nomadic pastoralism. They launched campaigns in South China, Vietnam and Burma, and in fact often overcame the logistical problems by using the know-how of sedentary peoples. On one occasion, they duped Hungarian peasants into coming out of the forest hideouts to collect the harvest, after which the Mongols massacred them and took the harvest for themselves.
Denis Sinor’s figures themselves are wrong. His figure of 120 acres of pasturage per year is based on American horse-breeder statistics. But American mustangs are, in fact, European domesticated horses. Horse generally needs 1 – 1,5 pounds of hay or pasture per 100 pounds of body weight every day, or 10 – 30 acres per horse for permanent pasturage. But American mustangs weight around 800 pounds. Mongol pony weights 600 pounds at most, and is much less demanding. Thus 120 acre figure could likely be reduced to 60 – 90 acres per year per horse, easily doubling potential Mongol force to 400 000 horses. Similar ecological theories are applied wherever Mongols failed, and are similarly unconvincing as a rule. Mongols were, in fact, militarily defeated by Mamluks in Syria (Battle of Marj al-Suffar, 1303), despite having allegedly retreated earlier due to lack of pasturage.

Mongol campaigns in the southern China, Russia and Iraq were successful despite the adverse environment of these regions, and they did impose their rule there. Conversely, they were unable to gain submission of states close to zones of significant steppe vegetation, such as the Byzantine Empire and the Sultanate of Delhi. In Russia, Mongols managed to hold onto the forests, but had to abandon the plains – an inverse of what should be expected.
Limited Goals Theory
Limited goals theory argues that the Mongol expedition was a punitive raid rather than an attempt at conquest. This is supported by the fact that Mongol campaigns of conquest, such as those in Korea and the Caucasus, consisted of a succession of invasion over the decades which eventually wore down the sedentary populations. Peter Jackson argues that the campaign was merely an attempt to punish the king of Hungary for harbouring the Cuman refugees, supporting it by citing Batu’s ultimatum to Bela: “I have learned, moreover, that you keep the Cumans, my slaves, under your protection; and so I order that you do not keep them with you any longer and do not have me as an enemy on their account.”.
Yet evidence shows that Mongols only raided when they did not have the manpower to subjugate an area. In many cases, campaigns of conquest devolved into raids due to an unexpectedly stiff resistance, as was the case with the war against the Jin dynasty. In Korea, campaigns took on appearance of raids because Koreans consistently reneged on the subjugation agreements, not because Mongols preferred to raid. And Jebe’s and Subetei’s “raid” of 1221. – 1224. was actually intended as an outright conquest, as Subetei had requested Chinggis Khan’s permission for creation of an occupational force.
Batu’s message to Bela was in fact a request for submission: “I am aware that you are a wealthy and powerful monarch … Hence it is difficult for you to submit to me of your own volition; and yet it would be better for you, and healthier, were you to submit willingly.”. It was a clear demand for surrender, further proven by the fact that Mongols had subjugated Bulgaria during their withdrawal from Hungary. Overall, the campaign was too large to have been a minor punitive raid. While Muslim authors ignored it due to their contempt for the West, Mongols themselves clearly considered it a serious undertaking. Army which marched against Europe contained a good portion of the Chinggisid dynasty. Even Muslim authors argue that it was a campaign of conquest, altough they falsely believe Europe to have been conquered by the Mongols (Rashid al-Din, writing in 1300., clearly states that Hungary and Poland are subjugated). Mongols themselves had expressed intentions to conquer not only Hungary but also countries beyond it. In fact, the title of Chinggis Khan translates as an “Universal Khan”, and as early as 1221. Mongol officials carried tablets proclaiming Chinggis Khan’s Mandate of Heaven – that is, sovereignty over the entire Earth. Less limited goals are hard to imagine.
Military Weakness Theory
The military weakness theory holds that the Mongols were weakened by battle losses incurred from 1236. to 1242., and thus called off the campaign. Unlike previous theories, this one is actually supported by period sources – both within and outside Europe. Carpini mentions that the Mongols suffered such great losses in Hungary that those who died in that campaign had their own cemetary, and that Batu was barely able to restrain his troops from taking flight at Mohi. His statements are supported by Yuanshi, a Chinese account which states that Batu became discouraged by his losses and expressed the desire to flee until Sübetei reproached him. Mohi was thus a very close run thing.
This was not a unique event. While Mongols did win every pitched battle they had fought, losses had been heavy in many of those. They were horrified by the losses suffered in the first surprise engagement in Poland at Czarna River, and had suffered a disaster besieging Kozelsk in Russia when the population had mounted a sortie, killing three sons of generals and thousands of troops.
Yet despite the stiff resistance, Mongols had conquered wide swathes of territory. By mid-April 1241., Russia was conquered, and organized resistance in Poland and Hungary had collapsed. Mongols remained in Hungary for a year. Panic spread as far as Spain and Netherlands, but all engagements Westerners fought against the Mongols amounted to minor skirmishes. Mongols never advanced in force to the west of Poland and Hungary.

Overall, the military weakness theory seems to have mostly been motivated by the nationalistic fervor.
Fortifications as a Reason for Withdrawal
The best explanation for Mongol withdrawal from Europe, and thus Hungary and Croatia, are difficulties they encountered with regards to Europe’s mass of fortifications. While each individual place may have been insignificant compared to fortified places in e.g. China or Korea, they nevertheless forced Mongols to engage in siege warfare which negated nomadic horseman’s advantages such as mobility. And both density and sophistication of fortified places increased with each westward advance.
While Mongols did succeed in taking many fortified places, such as in China, Europe nevertheless presented a unique challenge. Western Europe in particular was a difficult target. It was densely populated, with France and the Low Countries holding some 19 million people, Germany 10 million, and lightly populated Hungary and Poland around 2 million. Western Europe was also far more heavily fortified, with numerous fortified cities and castles. Mongols considered sending numerous Chinese Jin infantry against the West, but gave up due to logistical impossibility of such an expedition. Local infantry, unlike Mongol conquest of China, was not available: populace either resisted or fled, but few to none lords accepted Mongol rule, despite Europe’s political fragmentation.
When Mongols did invade, they encountered a variety of problems in the territory to west of Volga – such as dense forests and numerous populations. After the fall of Alan-Russian city of Magas, Mongols collected 270 000 ears, and did the same after the fall of Liegnitz. Only other reference to Mongols engaging in ear-collecting is their victory against a massive Jin army in early 1230s. This suggests that Mongols were very concerned with the numbers of enemies they were about to face. After the fall of Magas in 1239., divisions appeared in the Mongol leadership, centered on when and where the campaign could be acceptably terminated. Very few nations were submitting, and those that did submit tended to rebel immediately after the Mongols had left. Guyug lost his taste for the campaign and had to return to Mongolia in disgrace, but even the remaining commanders – including hardliners such as Batu and Subetei – were uncertain as to whether the campaign could be concluded successfully.
Mongols did have major successes in their initial invasion of Europe, as European armies repeatedly came out to fight them in the open field, falling victim to Mongols’ superior tactics and organization. But the Mongols overstretched themselves, and the Battle of Mohi was nearly a disaster for Batu Khan. In fact, Batu had expressed desire to evacuate Europe in early 1241. This desire will have only increased as European defensive strategy shifted from open battles to defense of strongholds, which in any case was preferred strategy in European style of warfare. Mongols marauded freely over Moravia and Croatia, but they were unable to do much damage as they couldn’t take fortified cities. Thomas the Archdeacon notes that “They remained in the region of Croatia and Dalmatia for the whole of March, during which time they descended five or six times on the cities, returning thereafter to their camp.” Seeing as how no coastal cities had been destroyed, it is clear that their defences successfully held off the Mongols. Hungarians held up Mongols for 10 months along the banks of the Danube, up until the river froze and allowed the Mongols to cross over. And earlier over the summer, Mongols were forced to reduce numerous improvised fortifications and strongholds constructed all across the Hungary. And eastern Hungary had lagged significantly behind the Western and Southern Europe in terms of both numbers and quality of fortifications, making it very vulnerable to Mongols. The commital castles of Hungary which Mongols had reduced were all nothing more than primitive wooden motte-and-bailey castles. Six castles which did survive were located on elevated sites, allowing them to survive Mongol bombardment.

Hungary in fact had only ten “new-style” castles, constructed out of stone and according to Western European practices. Five of those were along the border with Austria. But out of the other five stone castles – all of which ended up isolated and deep behind the Mongol lines – none were conquered by the Mongols, and all survived essentially undamaged. Western Europe by contrast had a very large number of such “new-style” castles, some of which were among the most impressive Medieval fortifications ever built. These new castles were constructed on elevated sites, and often were of the concentric design, allowing defenders a double line of defense where defenders on the inner wall could support the outer wall with missile fire. These stone castles were very large, and constructed according to what were essentially scientific principles of defense. Western European fortifications were markedly superior to their equivalents in Eastern Europe or Middle East. When Mongols entered Levant, they did not even attempt to take Crusader strongholds such as Antioch. While city of Sidon did fall to Mongols, its castle – where the defenders withdrew – was not even attacked by them. Mongol siege efforts in China relied heavily on the troops and expertise of local Chinese auxiliaries, but these were unavailable in the West. They could not even be gained through coercion, as the populace simply fled for fortified places or the mountains. This lack of familiarity with siege warfare often forced Mongol generals to demonstrate suicidal bravery in order to motivate the troops, with a large number of Mongol generals and even Chingisid princes dying in sieges. Sieges also saw frequent outbreaks of diseases in Mongol camps, such as cholera and the plague, which were in fact even more frequent than in the case of settled armies. Mongol armour was another liability, as while high-level lamellar was in fact superior to European mail, ordinary troops wore a leather armour which was a disadvantage in engaging heavily armoured opponents. Mongols in fact started looting European armour for their own use.
But even with heavy armour, Mongols did not like besieging cities, as it required them to dismount. A wide range of sources, such as Byzantine Strategikon and the Chinese manuals, note that nomadic tribes were not adept at fighting on foot. While Mongols had shown themselves able to reduce cities in Eastern Europe, they always suffered heavy casualties in doing so. Far more sophisticated Western European fortifications will have been a major obstacle. Mongols were well aware of this. In 1246., Guyug demanded that Europe surrenders its fortifications as a condition of peace. And after receiving report of Guyug’s conduct on the western campaign, Ögödei apparently wished to punish him by placing him in the vanguard to assault “the town walls which are as high as mountains.”.

Even worse for the Mongols, Europeans – much like the Chinese – possessed a crossbow, weapon which Mongols were particularly afraid of, and which was extremely deadly when used in defense of fortified places in particular. After the Mongol invasion, Bela IV took care to introduce the crossbow en masse to Hungarian military, among other reforms which will be described later.
This aversion to siege warfare easily explains why Mongols attacked some places and completely avoided others. While Western Europe had very strong fortifications for the period, this was not true in Eastern and Central Europe. Poland and Hungary were both attacked and suffered heavily in the Mongol invasion of 1241. Both kingdoms also lacked in stone fortifications. Polish border fortresses were made of wicker and earth, and even Krakow’s castle was made out of wood. As a result, Polish people sensibly abandoned their fortifications, hiding instead in forests, once it became obvious such fortifications cannot hold up to Mongols. But Mongol siege of the Wroclow castle in Silesia was a failure, and they refused to even try to besiege castle at Liegnitz after winning the battle outside. Fortified places in Moravia likewise escaped devastation, as they were strongly constructed by German settlers.
Fortifications in Hungary – Mongols’ main target – were particularly ineffective. Mongols easily broke through the border defences constructed of wood, and wooden comital castles were likewise ineffective. Beyond Danube, however, defenders fell back to 17 well-fortified places. City of Esztergom, with its wooden walls, proved unable to withstand Mongol assaults. Yet stone palaces proved able to withstand the Mongol attacks for a time, and had to be individually reduced. Mongols slaughtered the populace, enraged that citizens had destroyed all the valuables within the city. What wasn’t destroyed was taken to city’s stone citadel, which proved impervious to Mongol attacks. Mongol attack on fortress of Klis likewise failed: “However, the Tatars believed that the king was in the fortress of Klis, and so they began to attack the fort from all sides, launching arrows and hurling spears. However, the place was naturally well fortified, and they could cause only limited harm. So then they dismounted from their horses and began to creep up hand over hand to higher ground. But the defenders of the fort hurled huge stones at them and managed to kill a number of them. This setback, however, only made them more ferocious, and they came right up to the great walls and fought hand to hand. They looted the houses and took away no little plunder. But when they learnt that the king was not there, they abandoned their attack on the fortress, and ascending their mounts rode off in the direction of Trogir. All the same, no small number of them turned towards Split.“. Mongols, arriving at Trogir, offered the city a chance to surrender. Upon hearing defenders’ refusal, Mongols instead disappeared into the mountains.
But even the fortifications that did not hold out still meant an expenditure of men and time. Neither the king, the local conglomerations, or even the peasants, submitted without resistance. Adriatic fortresses completely stumped the Mongols, and Kadan attempted no major sieges. His attack on Dubrovnik achieved a whole lot of nothing, and it was only upon reaching Montenegro that Mongols started successfully reducing towns. After learning that Bela had withdrawn to an island, Mongols had no way of gaining Hungary’s submission except by systematically reducing fortified places one by one. Thus, they chose withdrawal, especially since conquered areas of Hungary were not fully pacified, and Hungary itself amounted to a salient deep into the enemy territory. Number of fortresses Mongols would have to face in any further westward push also made any further advance beyond Hungary impossible, as doing so would mean splitting up forces and risking a defeat in detail. Mongols conquered Balkan, whose inhabitants lacked the resources to build stone fortifications, yet nearby Greece escaped such fate – largely thanks to its stone castles. Mongols also never attempted to besiege Constantinople, despite its proximity to the Golden Horde. Extensive Byzantine system of stone fortifications makes it no surprise that the Emperor John III Vatatzes “sent envoys and after he got to know the Mongols, took little heed of them.”. He had nothing to fear, as Byzantines could simply retreat to castles and fortresses and wait until the Mongols left.

After the Mongol invasion, stone became the main material for castle building in both Poland and Hungary. Bela gave nobles the privilege of building castles, and his reign alone saw the construction of 66 “new style” fortresses across the kingdom, all built of stone on an elevated site. And upon the false alarm of Mongol return in 1246., Bela had the entire population of Hungary evacuate to fortresses, and also accelerated castle construction. But Mongols only returned in 1285., accomplishing very little thanks to Hungary’s new system of fortifications. Lesser Poland had similar experiences, with its network of stone castles built after the 1241. invasion allowing it to relatively easily – though not without losses – repulse the second Mongol invasion. Krakow in particular was noted to have had a stone citadel and many crossbows, and it apparently repulsed the Mongols with relative ease.
While China also had major fortifications and a large sedantary population, it fell to Mongols. But China had major weaknesses compared to Europe. Its fortified cities had no citadels to which inhabitants could withdraw, and it did not have European network of castles either. Chinese cities were also located overwhelmingly in open plains rather than on defensive sites usually chosen by European equivalents. Walls of Chinese cities were also structurally weaker than European equivalents, having been constructed of rammed earth with stone or brick facing. Yet even Chinese cities only started falling to Mongols after the latter had acquired skills and services of Chinese siege engineers. Jin resisted the Mongols from 1211 to 1234., but the eventual Mongol victory became inevitable thanks to cooperation of the Chinese themselves, who naturally had extensive knowledge of siege warfare. Many cities were also taken through defections of its rulers, as by the time of Mongol invasion foreign rule was nothing new to the Chinese. Jin dynasty itself was foreign, and its policies made many of its generals and governors rebel and join the Mongols instead. Jin capital itself was taken largely thanks to assistance of the Song army, which blockaded the city from the south. In the end, China was conquered by the Chinese.
Song themselves, despite facing a vastly increased Mongol empire which now could also rely on Jin auxilliaries for siege warfare, resisted for five decades. They also, preparing for Mongol invasion, decided to break with traditional Chinese construction principles. Instead, Yu Jue’s defense system resembled European castles, with fortresses being situated atop cliffs, but close to metropolitan centres whose officials could evacuate to forts. This new system performed brilliantly, with major offensives by Mongols in 1246., 1258. and 1259. all failling. Mongke himself was killed in the fighting at siege of Diaoyucheng. But while Yu Jue’s defense system had proven effective, it lacked depth – unlike the European castle system, new Chinese system was not widely adopted across the country. Fortified city of Xiangyang was thus besieged in 1268., but it resisted until 1271. when Muslim engineers sent by the Ilkhanate provided the besiegers with counterweight trebuchets. It should be noted that these weapons had originated in the Mediterranean, and were known in Europe and Middle East since before 1187. The version specifically used here – the double counterweight trebuchet or the bricola – had first appeared in Western Europe in the 13th century, and adopted by the Mamluks in 1250s. Rashid al-Din, who had no pro-European bias, plainly states that Frankish siege engines were brought to China and they were decisive in bringing a swift end to the war.

These trebuchets, capable of throwing stones ten times heavier than more traditional designs, quickly smashed the walls of Fancheng and Xiangyang. Fall of these two important cities caused the Song troops to defenct en masse and join the Mongols, and most of the cities followed the lead. Lin’an, the Song capital, capitulated in 1276. without offering any resistance. Song fell because their will to resist had been crushed. Yet that success was achieved by a force which more closely resembled European or Chinese armies than it did the traditional stereotype of the nomadic cavalry, or the force that had invaded Europe in 1241 (it should also be noted that the Great Wall of China was only built in 1368. – 1644. period).
Korea managed to resist from 1231. to 1259., thanks to strategic usage of island and mountain fortresses. Its fortresses were situated on hilltops, much like those in Europe. Mongol attacks on city of Kuju failed, and Mongols were forced to withdraw. Korean military dictator, Choi U, transferred the capital from Kaesong to Kanghwa Island, and built up a network of mountain fortresses. Mongols failed to take the fortresses, and their naval attack on Kanghwa in 1250s was a disaster. But while Korea resisted all Mongol attempts at military conquest, persistent drought and famine throughout 1250s combined with a high frequency of Mongol invasions destabilized the government. Fourth Choi dictator was assassinated, and the Koryo monarchy submitted to Mongols in 1259. But it is clear that it was internal events, and not Mongol attacks, which broke Korean resistance. And both Song and Korea had held out until the reign of a relatively benevolent Khubilai.
Mongols did manage to impose their will on much of the Middle East, which did have fortifications. But Khwarazm state was unstable, and many of its fortifications were in poor state. Its multiethnic nature also weakened its resistance, as the Turkic warriors charged with defending the cities felt no loyalty towards the citizens. As a result, in many cases the army simply abandoned the cities, leaving demoralized citizens to seek terms with the Mongols. Samarkand was turned over to Mongols by the troops defending it. In general, mercenary character of the Central Asian armies made defense impossible, as no walls are of any use if they are defended by the soldiers which identify with the invaders rather than with the citizens. Multiethnic and unstable nature of the Khwarazmian state led city after city to seek terms with the Mongols, despite the latter’s treacherous nature. Another reason was that walls of cities in the region were built of mud bricks. While still somewhat defendable – city of Otrar held off the Mongols for five months until the treachery allowed the Mongols to enter the city – they were relatively easily breached, and the governors knew this.
Yet Mongols, despite overruning the Seljuk realm quickly, never invaded the well-fortified Lesser Armenia. Armenians accepted Mongol overlordship as a balance against the Muslim enemies surrounding them, and Mongols granted them special privileges, which Marco Polo notes happened specifically due to strength of Armenian fortresses. When Mongols attacked the Assassins, they achieved successes – but not by conquering fortresses by force. Rather, young imam Rukn al-Din, thoroughly cowed by Mongol display of force, surrendered, and also ordered all the other fortresses to surrender. Likewise, fall of Baghdad in 1258. was partly due to various parties in the city siding with Hulegu, upon which the caliph ordered the city to lay down the arms. Final engagement in the long conflict was likewise an unsuccessful Mongol siege of a Mamluk fortress.
Mongol campaigns against Sultanate of Delhi likewise failed to accomplish much. Climate was not an issue, as Mongols wintered continually in Punjab in 14th century. They also had a very keen interest in conquering India due to its riches, and in 13th century had repeatedly attempted to conquer Bengal but without success. Genghis Khan’s siege of Multan in 1223. was a failure. Attempts in late 1230s and 1245 were likewise failures due to inability to capture key cities. From 1240s all the way to 1280s, Mongol invasions were characterized by unsuccessful sieges. Even major invasions launched in 1299. and few years later, both with armies of over 100 000, both failed due to inability to take fortifications. Sultanate also showed unwillingness to negotiate with the Mongols, preventing them from gaining through deception what they could not through force of arms. At the same time, Indian fortresses – built of stone, situated on raised sites, and well supplied – were essentially invulnerable to Mongol attempts at taking them.
Conclusion
In the end, it seems clear that Mongols withdrew due to a combination of factors. Main reason however was a strong network of well-fortified places in western Hungary and southern Croatia, many of whom were constructed by Romans prior or during the great migrations of 4th – 7th centuries. These stone fortifications could resist the Mongols for as long as the will to resist was present. Mongols could easily capture wood, earthen and mud brick fortifications as these could be breached by Mongol artillery in short order. Stone fortifications could not, and thus allowed the resistance to continue for so long as the will to resist was present and fortifications were not captured through ruses. Europe and India both resisted Mongol conquest thanks to strong stone fortifications and unwillingness to negotiate. Both of these factors were present in the (western) Hungary and Croatia, and thus Mongol conquest of these areas was not a realistic possibility.
Europeans also had a will to resist that was in many cases not present elsewhere. Seeing (and largely correctly) Mongols as deceitful pagans, Europeans concluded that the armed resistance, however costly, was the only logical option. Thus there was very little active collaboration. And this fact preserved the Europe from destruction and genocide that Mongols had caused essentially everywhere else. This, and the lack of counterweight trebuchets in the Mongol arsenal might have saved Europe, as such weapons were successfully used by the Mamluks to reduce the previously unassailable Crusader strongholds in the Holy Land.
Hungary itself was in a relatively bad position vis-a-vis any prospective Mongol invasion due to a combination of geographic and sociological factors. But this did not preclude successful resistance. Its castles had proven a major obstacle to conquest, which was recognized at the time. This is proven by the flurry of castle-building activity that had occured after the Mongol invasion: some 147 to 172 new castles were built between 1242 and 1300. This occured however primarily in the areas that were less affected by the invasion, and so new castles were concentrated in the western and southern areas of the kingdom. Another element of this was that these areas had a hilly terrain suitable for construction of new castles.
Reblogged this on Defense Issues.
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