THE INVASION OF THE CHRISTIAN WEST BY THE TATARS (MONGOLS). A CLASH OF CIVILIZATIONS BETWEEN FREDERICK II, GREGORY IX AND THE TATARS*

Research objectives: The author of this article wants to show how the clash of two different civilizations, until then practically unaware of the other’s existence, the Tatars and the Christian West, undermined the superior and self-confident position of the latter. In the author’s view, Western Christian Society in the first part of the thirteenth century regarded itself as superior to other civilizations. This article is not focused on either civilization, but tries to unveil motives, background and perspectives from both sides’ attempts to try to be the strongest power and the most important civilization at that time. In the Christian West there was a constant struggle for power between the Pope and the Emperor, going back to the Investiture Controversy of the eleventh and twelfth centuries and culminating in the conflict between Emperor Frederick II and the papacy in the thirteenth century. At the height of that struggle, in 1241, the Tatars (Mongols) invaded Hungary and Poland. Western Civilization was threatened, although at first almost nobody realized the danger and underestimated the consequences. It was due to the superior tactics of the Tatars that they surprised the Christian West. The Tatars were far better in their communication, strategy and information than the divided society in the West. The Tatar invasion, through their use of a kind of Tsunami Strategy, had all the necessary ingredients to destroy Western, Christian society. Research materials: By using contemporary sources and books that illuminate the Tatars as well as the Christian West, the character of the conflict that took place becomes clear. Results and novelty of the research: The end result was a clash of civilizations, an explosive mixture of a political-cultural conflict, a time-bomb which ultimately, narrowly, failed to explode, thanks to a sudden and somewhat mysterious retreat of the Tatars, but leaving Western Civilization faced with an existential crisis that undermined Western

world was supposedly nigh [19, p. 14]. Since the Tatars had 'broken open the gates' by invading the West, it was feared in the 13 th century that the world was coming to an end -an eschatological approach, so to speak [19, p. 13-14].
The Tatars were supposedly descended from one of the sons of Japheth, a biblical figure named Gog, ruler of the land Magog, which was a synonym for apocalyptic threat 6 . The characteristics of the Tatars and their native country ostensibly referred to a kinship with Gog and Magog. In the last book of the New Testament, Gog and Magog belong to the peoples 'of the four corners of the Earth', which were to follow Satan to the last battle against the saints, and subsequently be destroyed by heavenly fire. In short, we're talking about God's punishment for human wickedness. The Dominican Ricoldo de Monte Croce explained the origin of the name which was to be used so much in later eras (and even today): Mongols. According to him it derived from Mogogoli, the sons of the legendary Magog. In the legend, Gog and Magog were two giants, who had long ago terrorized Europe with their plundering. They were defeated by Alexander the Great, and locked up behind massive gates in the Caucasus. Their descendants had now broken free, and had taken it upon themselves to destroy (Western) civilization. Western Christendom used these myths and legends to explain the disastrous Mongol invasion. The pope feared that Christianity itself would perish: "we shudder to think that through these Tatars, the name of Christ could be completely laid low" [11, p. 12-13].

How were the Tatars perceived in Europe?
Up until the start of the 13 th century, people in Europe were barely aware of the existence of the Tatars. Now and again reports trickled through about a great the Chinese practice. Possibly by association with Tartarus (hell or the Underworld in Greek antiquity) an 'r' is added to the name, and people tend to speak of 'Tartars' or 'Tarters'. The 'Empire of the Great Khan', the Eurasian territories conquered by Mongol rulers, would from then on be known as 'Tartaria' or 'Tartaria Magna' (Great Tartary). This practice would continue for centuries after the disintegration of the Mongol empire. For Nicolaas Witsen and his contemporaries in the seventeenth century the name 'Tartaria' or 'Tartary' was the normal name for the Eurasian steppes" (http://resources.huygens.knaw.nl /retroboeken/witsen/dutch_intro.pdf). Mongols and Tatars were originally two different nomadic tribes in the river Orchon's basin in North-East Asia, on the border of the present day Russian Federation and China. Both names were later used to indicate ethnic conglomerates. The name Tatars was used mainly by Russians and Chinese. Chinggis Khan and his successor preferred to identify both themselves and a number of assimilated peoples as Mongols. Tatars had murdered Chinggis Khan's father. The name Ta(r)tars has fallen into obscurity in the West, but not in Russia. With gratitude to prof. Naarden for this information in his e-mails of April 1, 4 and 8 of 2016. 6 There are only a few characters who, like Magog, are present in both the first book of the Bible (Genesis) as the last (Revelations). The story of Magog begins in Genesis 10. This chapter groups all then-known peoples after their relation in history and place of origin. Japheth is a son of Noah. The 'sons of Japheth' are: Gomer, Magog, Madai, Javan, Tubal, Mesech and Tiras (Genesis 10:2). These 'sons' tend to live in Asia Minor. According to the Bible, Magog and his family travel to a place where they can grow into a tribe. This is why Ezekiel does not refer to Magog but 'Magog's country' (Ezekiel 38:2). In Revelations 20:8 only peoples are left: "and [he] will go out to deceive the nations in the four corners of the earth-Gog and Magog-and to gather them for battle. In number they are like the sand on the seashore." Gog and Magog are now portrayed as the ancestors of the Islamic peoples. Magog represents the central Asian peoples (the Islamic republics in southern Russia and Afghanistan) and Gog the peoples south of the Black and Caspian Seas. horse-people in the East, which was becoming more and more active militarily, but it was not considered a threat just then. Under Pope Gregory IX (1227-1241) especially interest in this people grew. The East was seen as an area ready for conversion. For this reason, several clerics were sent out to make contact with, and gather information about, the peoples in the East. Among them were Archbishop Robert of Esztergom (also called Gran) (1227), and the Dominicans Otto (1233) and Julian (1236; recorded by his fellow Riccardus in 1237). Later, after the Tatar retreat from Europe, journeys were focused on diplomacy and missionary work in the Mongol Empire. Of these, the reports of the Franciscan John of Pian del Carpine (1245), the Dominicans Ascelin of Cremona (1245) and André de Longjumeau (1248) and the Flemish Franciscan William of Rubroeck (1255) are among the most well-known.
The first substantial description of the Tatars was made by the Dominican Julian [7, p. 34] 7 . He undertook two missions into (modern) Russian territory. However, he was forced to abort his second mission because of the growing threat of a Tatar attack. His reports made two things clear: first, that the Tatars were preparing an attack on the West, and second, that many peoples who lived there were ready to convert to Christianity. The imminent Tatar attack became the main focus in his reports. Julian makes clear that the Tatars were not just a nomadic people, as was long assumed, but a people with clear bellicose intent. He wondered what kind of people the Tatars actually were, where they came from, what their history was, what strategy and weapons they used, and what their intentions were. He lacked the time and peace to paint a proper, complete, and well-founded picture. Tatar daily conduct and customs barely feature in his reports, even though that was originally his intention. His observations contain reliable elements, and are not dominated by Christian and Western imagery. They represent the way the peoples of the steppes think and act, especially during fights and raids, like the thought of vendetta: vengeance and taking justice into your own hands when treated unjustly. For instance, it is said in his reports that most Tatar women did not participate in battle (though at the end of his report he points out that the Tatar women actually took part in the battles). Their main task was advisory and educational. After a victory in battle the captured women were both spoils of war and property of the victors [3, p. 45-46]. Especially the last part of Julian's descriptions is historically relevant, because it's an important source for the first Tatar campaigns in Russia, and for the Tatar conquest of Persia. This shows that the motive for fighting gradually changes from vendetta to claims of global rule, in which power and conquest are key elements. Julian was in awe of the huge size of the Tatar army. He was most impressed by its organization, its bowmen, and the tactics which were used. The army was a motley crew of different peoples, but command was always exercised by Tatars.
Julian was the first westerner to fairly comprehensively and accurately report these observations. Incidentally, he managed to obtain a letter from the Tatar leader Batu Khan (more about this later) to the king of Hungary, Béla IV. This letter is the earliest known example of Tatar diplomacy to the West. The letter made clear that the Tatars didn't just plan to conquer Hungary, but also Rome and further territories [3, p. 47; 4, p. 140; 5, p. 177; 7, p. 37; 9, p. 67 ff] 8 . Julian took this letter very seriously indeed, and handed it to the papal emissary in Hungary, who was both a representative of the curia and an advisor to the king of Hungary. Whether the emissary actually informed the curia remains uncertain. The fact remains, however, that Béla IV was unimpressed by the letter, probably because previous attacks from the east had always been repelled, and the danger did not seem greater than before. In short, the message was not given any priority. Julian's prior warnings were only brought up after King Béla lost the battle with the Tatars. This prompted the Emperor Frederick II to accuse King Béla IV of negligence, by assuming all along that he was secure, when all the while he had been receiving numerous reports from and about the Tatars, but had done nothing to prepare or defend himself.
A year or two after this letter, new reports about the Tatars reached the West through a Hungarian bishop. Copies of these messages reached England and are preserved in the Chronica Majora of the Benedictine monk Matthew Paris (Matthaeus Parisiensis), and also on the Annals of Waverley (an abbey in the county of Surrey) [1, p. 324 ff] 9 . The letter was reportedly written by a Hungarian bishop to the bishop or arch-dean of Paris. The letter states that scouts had established that the Tatars had come very near to the Hungarian border. The bishop's final conclusion was that the Tatars would invade the West within five years. In reality, the invasion would come even sooner [1, p. 325; 3, p. 56-57]. Representatives of an Islamic-Shi'ite sect unexpectedly appealed to the kings of France and England for military aid 10 . This came about because the Tatars had started a campaign of conquest in Persia and the Caucasus. It seems remarkable that this sect appealed to the West for aid, but they had little choice because they were considered heretics by the rest of the Muslim world.
In his Chronica Majora Matthew Paris describes the approaching calamity of 1238 like this: "About this time, special ambassadors were sent by the Saracens, chiefly on behalf of the Old man on the Mountain 11 , to the French King, telling him that a monstrous and inhuman race ("homines monstruosi et inhumani") had burst from the northern mountains, and had taken possession of the extensive, rich lands of the east; that they had depopulated Hungary Major (the region between the Volga and the Urals; H.K.), and had sent threatening letters, with dreadful emissaries; the chief of which declared that he was the messenger of God on high, sent to subdue the nations who rebelled against him (...). This powerful and noble Saracen messenger, who had come to the French King, was sent on behalf of the whole of the people of the East, to tell them these things; and he asked assistance from the Western nations, the better to be able to repress the fury of the Tartars: and he also sent a Saracen messenger to the King of England (Henry III; H.K.), to tell these events and to say that if they themselves could not withstand the attacks of such people, nothing remained to prevent their devastating the countries of the West" [3, p. 63-64; 11, p. 131].
It is likely that this event caused Matthew Paris' attention to pique. From then on, he annually reported about the Tatars. From 1241 onwards, after the Tatar incursion into Europe, he alters his tone. He then starts using negative terminology when describing the Tatars, as is apparent in the following quote from the Chronica Majora from 1241: "The men are inhuman and like beasts, they should sooner be called monsters than men. They are thirsty for blood, which they drink, they tear and devour the meat of dogs and men, they dress in bull-hide and are armed with iron lances. They are short and stocky in body (…), their strength does not wane, they are invincible in war and indefatigable in their toil. (…) They know no human law, have no pity and are more ferocious than bears or lions. (…) They know only their own language, and no other people has learned it" [14, p. 76-77]. And: "(…) All those who viewed the enemy's army from on high were appalled by the inhuman cruelty of these henchmen of the Antichrist, and told the governor about the horrible wailing by his Christian subjects, who were surprised and brutally killed in all adjoining provinces, no matter their rank, position, age or gender. The Tatar chieftains and their inhuman barbarous followers feasted on the corpses of the inhabitants and left only gnawed bones for the vultures; it was remarkable, however, that the greedy and insatiable vultures refused to touch the scraps left by the Tatars. Daily, old and crippled women were given to their cannibals for nourishment. Young and beautiful women were not devoured, but were overpowered even as they wept and wailed in their violent and unnatural defilement, the breasts of tender virgins cut off to serve as delicacies for their leaders, their bodies used as sustenance" [20, p. 50-51].
The image of the Tatars in the West in the 13 th century was far from reliable, aside from some astute observations by Julian. Stereotypes and prejudices were all around. Europeans had gotten quite a shock when it became clear that the Tatars were truly at Europe's gates. Despite all the warnings, people in the West were still not aware of the true scale of the Tatar threat. Even worse, there was a certain carelessness fueled by recognition of the Roman primacy among ever more people [10, p. 61].

Was the invasion of the West a surprise?
In the end of 1237 and the beginning of 1238, the Northeastern-Russian towns of Vladimir, Rjazan and Suzdal came under attack, followed in 1239 by the southwestern areas of Russia; by 1240 the entire Caucasus was under Tatar control. King Béla of Hungary supported his allies, the Cumans, a nomadic people from southern Russia who inhabited the steppes of southern Russia, and even offered them asylum in his own kingdom, but in 1241 both Poland and Hungary had to face the music [10, p. 73].
Reactions to the invasion of Europe went through three stages: first unbelief, followed by the belief that the Apocalypse, the end of the world, was about to come, and finally a rationalization of what really happened [6, p. 293-299]. The unimaginable, unreal idea that Europe could be invaded by a former steppes people, acting like a horde of barbarians, can best be illustrated by the following quote: "Only God knows who they are and where they come from. (…) We don't know where they come from and where they went. Only God knows whence He found them to inflict them on us, as a result of our sins" [6, p. 293].
To the inhabitants of Europe the invasion came as a complete surprise. In 1241, Matthew Paris wrote that the Tatars had crashed into Europe like a 'sudden bolt of lightning' [6, p. 290]. We have already seen, from the reports of the two missionary journeys that the Hungarian Dominican Julian had undertaken in the region of the Urals between 1235 and 1241, that this clap of thunder had come less sudden and as less of a surprise than Matthew makes out here. Those reports however were not acted upon. Another clear sign, communicated through an emissary of the Great Khan Ögedei, notably the Tatar resolution to conquer Rome and the Western world, was similarly ignored. Finally, there was the aforementioned letter from Batu sent via Julian to the Hungarian King Béla IV, demanding his surrender [3, p. 41]. Such letters and messages were intended to demoralize opponents in advance. But why should Europe take action? Hungary had been resisting attacks by steppes-peoples for centuries. Why would it be different this time? Frederick II was later to describe this careless, lethargic attitude of Béla IV as gross negligence [10, p. 62; 15, p. 57] 12 . It was only after the fall and sack of Kiev on December 6 th of 1240 that the king felt obliged to take securitymeasures, though these were scoffed at by the Tatars. In a letter to his brother in law, King Henry III of England, Frederick II told of the fall of this city. "Kiev (Cleva), the biggest city of the kingdom, was conquered, just like the entire kingdom, its inhabitants defeated and its countryside turned into a desert" [7, p. 39; 8, p. 514]. With the western part of Russia conquered, the road to Poland was clear, and a part of the Tatar army marched on to Cracow and Breslau. To prevent Polish and Hungarian princes from assisting each other, the Tatars decided to simultaneously invade in three places: in Poland, Transylvania and Hungary.
On March 18 th of 1241 Cracow was razed 13 . A few weeks later, on April 9 th of 1241, a German-Polish cavalry army was annihilated at Liegnitz (in German: Wahlstatt). In the battle, the Tatars were commanded by Kaidan (Qāidū) and opposed by the Kingdom of Poland, led by Henry II the Pious of Silesia, and supported by the Teutonic Knights and a cavalry army from the Holy Roman Empire. Tactically, the Tatars were very strong, alternating between feints and retreats to wrong-foot their opponents, and employing swift counterattacks.
This battle claimed the life of Henry II the Pious of Silesia. The Tatar strategy at this battle was aimed at protecting their own main army, which was marching on Hungary, in order to prevent the Poles to send assistance to Hungary. Aside from tactical tricks, they made use of existing disagreements between the Polish 12 Frederick II himself later admitted that he had underestimated the Tatar threat. See below. Incidentally, Frederick II and Béla IV did not really get along, because Frederick II blamed Béla IV for not openly taking the Emperors side in his struggle with Pope Gregory IX. This was one reason of many why he entered into negotiations with dissatisfied Hungarian nobles to depose Béla IV as king. 13 According to tradition, a bugler plays a melody on a golden trumpet every hour in the highest tower of the Church of Our Lady Assumed into Heaven (Polish: Kościół Mariacki) in Cracow. This melody is played to warn the city of the imminent Tatar attack, and is played four times: one for each cardinal direction. During the fourth melody, the bugler suddenly stops. Ostensibly, the original bugler was killed by an arrow to his neck, which is why the melody is not completed. command to attain their goal. After the Battle of Liegnitz, the Tatar troops eventually reunited with their main army in Hungary.
By simultaneously placing a second attack, the main army, under the command of the Tatar military leader general Batu Khan (also spelled Bātū), Chinggis Khan's grandson, was able to invade Hungary. The Tatars once again used the same tactics of encirclement that had proven so effective in earlier battles: they attacked King Béla's army from five different directions, utterly overwhelming it. The Hungarians had underestimated the Tatar danger, their courage, offensive power and tactics completely. Béla's army had far superior numbers, but it suffered from severe lack of cohesion. Furthermore, the nobility was seriously displeased about some of the decisions made and the policy employed by Béla. His authority had eroded [7, p. 46] 14 . On April 11 th of 1241 a huge battle took place near the Hungarian town Muhi, to the southwest of the river Sajó: the 'Battle of Mohi'. King Béla had failed as military leader and committed several tactical gaffes, but by a miracle he and his brother Koloman managed to evade encirclement and capture 15 . To Batu however, Hungary remained unconquered as long as the king was at large, especially since the king had dared to refuse the great khan's orders. The fleeing king was pursued through Slavonia and Croatia, to the Dalmatian coast [7, p. 55] In the meantime, it was estimated that the population of Hungary had been reduced to half its number as a direct result of the Tatar invasion [7, p. 62] 16 .
Most towns, castles and monasteries in Hungary were barely walled and practically indefensible, and were easy prey for the Tatar onslaught [10, p. 64]. The surviving population was systematically and premeditatedly slaughtered, to serve as a horrible deterrent to would-be resistance against the Tatars 17 . The Battle of Mohi was given great symbolic meaning, not just because the loss of this battle meant that all of Europe came under Tatar threat, but also Christianity. According to contemporaries, as a result of this event a state of panic ensued in the West, reaching both Spain and the Netherlands [10, p. 65] The preparation and execution of the Tatar campaigns against Poland and Hungary reveal careful, well-thought out and strategically perfect planning. These were preceded by 'diplomatic' dueling on the heels of Tatar demands of subjugation. If this was refused, a brutal and merciless reckoning would follow [7, p. 41]. 14 A well-known incident tells of the Austrian duke Frederick II who intended to support King Béla IV in his battle against the Tatars. He refused to have his soldiers fall under the command of the king. When that threatened to happen, he took his troops back to Austria. There had been incidents and tensions with other leaders and groups, leading to conflicts with King Béla, preceding Duke Frederick's decision. 15 After the Tatar retreat Béla IV himself returned to Hungary, where his main focus turned to constructing a system of defense utilizing castles to repel the threat of a new Tatar attack. This attack did indeed come in 1261. This time Béla was more successful and managed to defeat the Tatars. Béla has great renown in Hungary, and is commonly known there as "the second founder" of the kingdom. 16 Of the ca. two million Hungarian inhabitants almost one million perished, about half of them in battle and the other half by hunger and disease. 17 The most important chroniclers, Roger of Apulia and Thomas of Split, both give a similar description of the events and horrors.

The Tatar army's formula for success
There are different ways to account for the unprecedented success of the Tatar attacks. Perhaps the Tatar military superiority is best explained as a combination of strategic insight, mobility, organization, discipline, strike force and flexibility. The Tatar army possessed great herds of horses, and its soldiers were toughened and lived a sober life. As is reflected in his reports, the Dominican Julian was highly impressed by what he saw and heard about the Tatar army [3, p. 48-53]. Its horsemen rode small, agile horses, and they were able to fire arrows while mounted -and their arrows had a greater reach than any contemporary Western army. These arrows could penetrate armor, whereas the Tatar's own protection consisted of strips of boiled leather tough enough to resist the enemy's arrows. Commanders were able to easily move large units by using their widely enforced discipline, in stark contrast to the more individualistic way of making war employed by the Western knights [10, p. 71].
The female warriors that fought along with the men were just as warlike, just as skillful and just as brave as the male warriors. According to Brother Jordan (quoted by Matthew Paris): "Their women ride in full armor and spare no-one. The woman who fights best, is seen as desirable, as it is with us with the women who weave and sew best" [3, p. 49, 69]. The army was a well-oiled and highly disciplined fighting machine. It was divided according to a decimal system: units of tens, often consisting of allies of non-Tatar origin, lead by Tatars who in turn where part of centuries lead by a "centurion". Allies were allowed their customs and traditions, providing they obeyed the Tatar warlords' commands. In battle, the tactics used often consisted of provoking the opponents, followed by encirclement and attacks in wave after concentric wave. In doing so, the Tatars used scouts who could relay messages over great distances by using an ingenious system of signaling by flag. This method of communication also allowed for different Tatar units to keep in contact with each-other. Another tried tactic was the use of hostages as a living shield. They were forced to form the vanguard, often only armed with spears. If they attempted to flee, they were killed, which is why they were very fierce in their attacks: they had nothing to lose [3, p. 50].
Another relevant point was the composition of the opposing armies. The Hungarian army primarily consisted of knights who, due to their heavy armor and crude weaponry, were far less agile than the Tatars. It was an army, moreover, that lacked unity, was lead poorly, and whose separate units did not know what the others were doing. The Tatar army had a much better organization and leadership, and also had at its disposal 'modern' weaponry, like huge crossbows and the thenrecently discovered gunpowder from China [11, p. 96]. But the most important thing about the Tatars was their strategy, also described as Tsunami Strategy: they struck a certain designated region, flowed over into others where they inflicted a considerable amount of devastation and then they returned to the 'flooded' area, i.e. the area which was struck first and was the target of the campaign [12, p. 31-36]. Significantly, defenders were generally overwhelmed by the use of multiple invading armies, and relentless pursuit of military leaders. The point of this method was not to simply conquer huge swathes of territory, but to conquer a designated region and by using forays and destructive raids, create a buffer around the annexed region. Secondly, this method made it much more difficult for opponents to organize resistance, because the apparent leadership (like King Béla of Hungary) was not given the chance to make contact with his vassals and allies. The Tatars then governed and controlled the newly annexed area while their armies remained on the frontier [12, p. 31-36]. All this explains how a numerically inferior Tatar army could defeat a far larger Hungarian army [10, p. 71] 18 . In short, the Hungarian army was ill-prepared for the coming of the Tatar army, and the tactics it would employ. For that matter, the same could be said of European knightly armies in general.

The struggle between Emperor Frederick II and Pope Gregory IX
At the time that the Tatars were invading Europe, the Emperor Frederick II and Pope Gregory IX were engaged in a fierce struggle. This struggle had a long preliminary history, a history of mounting, reciprocal distrust. The seeds for the troublesome relationship between Frederick II and the pope were sown in the German town of Aix, where the then twenty-years-old Frederick was crowned King of the Romans in 1215 and promised to go on crusade. This promise was repeatedly deferred, for different reasons. When pope Honorius III in 1225 once again called upon Frederick to go on crusade, he threatened him with excommunication if he did not depart. Eventually Frederick departed for Jerusalem from Brindisi in 1227, but he fell sick en route and returned to Italy. Upon hearing this, the new pope Gregory IX (Honorius III had died in March 1227) promptly excommunicated the emperor because he felt his illness was just another excuse. When Frederick was cured, in 1228, he finally departed, but now as an excommunicate. Once in the Holy Land, he succeeded in winning Jerusalem for a period of ten years, by engaging in diplomatic negotiations with the Muslims, who were lead by the sultan Malik al-Kamil (full name: al-Malik al-Kamel Naser al-Din Abu al-Ma'ali Muhammed). This crusade is known as the Sixth Crusade (1228-1229).
The pope, however, was dissatisfied: that an excommunicated emperor had won the city of Jerusalem in the name of the Western Christendom was a contradictio in terminis. In the summer of 1229 Frederick was forced to return to Sicily, because the pope was attempting to take control over Sicily into his own hands while Frederick was absent. Frederick quickly succeeded in taking control of the situation, but his relationship with Pope Gregory IX was seriously damaged. Gregory was forced, by his military weakness, to come to an arrangement with Frederick. Peace was signed in San Germano on August the 28 th of 1230, and Frederick's excommunication was lifted. Despite the peace, neither Pope Gregory nor Frederick was really willing to adjust their opposing views about the primacy in secular power. Their mutual relationship quickly soured, when it was discovered that in the struggle for the North-Italian cities none of the parties was willing to compromise: not Frederick, not the pope, and neither were the Italian cities of the Lombard League.

Two opposing worlds
The pope and the emperor represented two opposing, irreconcilable worldviews. Since the second half of the 11 th century, popes no longer saw themselves as 'merely' the successors of St Peter, but also as the vicar of Christ. Gregory felt that he, as pope, could act as judge over the secular princes. Although according to political-theological views both emperor and pope receive their station directly from God, the church felt it had the right to adjudicate over the worldly leader due to his sinfulness as a human. Frederick however, like his grandfather Frederick I Barbarossa before him, was convinced of equality between pope and emperor. The emperor wasn't just pre-ordained by God, he received a clerically similar sacral status through the anointment with chrism during the ritual of coronation: the ruler was the anointed of the Lord. From this followed his political position that God had instructed him to bring peace and justice, and he was accountable to no-one. Tensions between pope and emperor mounted to such an extent that Frederick was excommunicated for a second time on March 20 th of 1239. At this new excommunication the pope portrayed Frederick II as a 'selfproclaimed heretic' and 'the beast of blasphemy from the Apocalypse'. This time, the excommunication would not be lifted. Because Frederick refused to accept the pope's authority over the worldly princes, and because he posed a threat to the independence of the Roman church, Gregory was determined to subdue Frederick by any means necessary. All of Europe was drawn into the ensuing propagandabattle, which was unprecedentedly sharp in tone on both sides [16, p. 41-71]. The Tatar invasion, however, was not just a threat to Hungary, but to the entire Christian West. The 'libertas Christiana' was at stake. The Tatars became part of God's plan for the world. They were seen as a scourge and a tool of God, used by Him to punish the Christians for their sins and the princes and prelates in particular for their carelessness. And so an appeal for intervention to both pope and emperor was to be made. The appeal, however, did not lead to a reconciliation between both parties. Mounting a united offensive against the Tatars was instrumental, but the odds of that happening seemed more remote than ever. Who was the true leader of the world, the pope or the emperor?

Who will save the Christian West?
There is a sense of gross underestimation of the scale and urgency of the Tatar danger in the letters that Frederick wrote to the other European monarchs, like his brother in law Henry III of England. The emperor appealed to all to unite and stop the Tatar enemy, and in this way 'to fight for peace'. He was well aware that due to his bad experiences and relations with the pope, a united stand against the Tatars was out of the question. However, by showing his good intentions, he could demonstrate to the world that the lack of forceful action against the Tatars was not his fault. His letters emphasize that he was unable to act without peace between himself and the pope, warn against the Tatars exploiting the disunity in the Christian world, complain of the pope preaching a crusade against him instead of the Tatars and Muslims, and reaffirm his readiness to mount a new crusade. In short, he wanted to maximize any advantage he could glean from the situation and apply it in his conflict with the pope [10, p. 67]. For instance, he had the Hungarian emissaries who had delivered Béla IV's urgent appeal for help ride to Rome to appeal to the pope not to jeopardize Christianity. The pope had to realize that he would be risking the future existence of the Christian faith if he prevented the Emperor and the other monarchs from mounting a united defense against the Tatars. He subsequently wrote a letter to Béla in which he hoped that the pope, in the moment of truth for Christianity, would take away the restrictions which had prevented Frederick from intervening immediately and by all means at his disposal stop and destroy the Tatars. This was of course a reference to his renewed excommunication, and the threat of deposition which he was facing [18, p. 504-505]. Finally, on July 3 rd of 1241, he wrote a long entreaty to Henry III of England. In this letter he made an appeal to face the Tatars together. In passing, he mentioned his apparent demonstrations of humility towards the pope, and fulminated about the ongoing and systematic way by which the pope obstructed him in his duty of making peace and justice prevail. He grandiloquently writes: "O God! How deeply and how often would We have let ourselves be humiliated and have We demonstrated all good will, if only the Roman Pope would dispense with his annoyance over the rift between Us, which annoyance he has cast out over all the world, and would temper and cease altogether his efforts, which betray the impetuosity of unrestrained passion, and allow Us to reign in peace over those who by law are Our subjects and keep them in obedience, and no longer protect and strengthen a great part of those who have risen in rebellion to Us, so that after We have brought peace to our realm and chastened the rebels [meaning the Tatars, H.K.] against whom We have expended infinite treasures and mounted the greatest efforts, Our power would exalt magnificently and turn towards the common opponents" [8, p. 516-517].
Frederick continues by suggesting to Henry III that it's past time that the Christian West should unites in its common interest to 'send the Devil back to Hell': "May your highness therefore take precautions, and while those common enemies fight their battles in the neighboring realms, look to thyself, to resist them with swift aid; for they have prepared themselves within their own lands to, with complete disregard for their own lives, subjugate the entire Christian West, may God forbid it, and to extirpate the Christian faith and the name of Christ. (…) But we have hope in the Lord Jesus Christ, under whose guidance we have so far, without enemies, triumphed, and that those too, who have crawled forth from Tartarus [Hell, H.K.], will fall down into their own Tartarus after they have felt the power of the Christian West, and experienced its resistance" [2, p. 241-242; 3, p. 77; 8, p. 518].
The timing and the content of his letters show, that Frederick initially underestimated the threat of the Tatars, but also that he subsequently accurately assessed the implications of the invasion. He was well-informed about the Tatar warriors, their martial prowess and the imminent danger. In going about this, he employed the same style of approach as he did in his famous book about falconry (De Arte Venandi cum Avibus): that of an astute observer and analyst 20 . He then assessed which allies he would need in his fight against the Tatars. He reached out for aid in this fight to kings all over Europe and the pope. By acting in this way he gave a special meaning to his imperial status: he was at that time the most prominent person to save the Christian West from its doom. The pope should be grateful to him for that. He could show his gratitude by withdrawing all the accusations against him, and to rescind the upcoming trial, which was intended to depose him as emperor.
But that didn't happen. The pope answered Béla IV in a businesslike, nonapocalyptically toned letter, saying that he most definitely realized the danger. He promised to do everything that was in his power to give aid. He appealed to all the monks in Germany to pray for a positive outcome. The rest was up to having faith in Gods charitable aid. He could not help but reference his struggle with the Emperor at the end of the letter. According to the pope, it had been Frederick who had weakened the fight against the common enemy. He simply reversed the question of guilt: if the Emperor had been willing to show his humility, atone for his wrongdoings and to bend to the commandments of the church, Hungary would be able to receive the unrestricted support of the entire Christian community in the West. In this way both pope and Emperor tried to use the Tatar invasion to force the other to concessions, but neither was willing to take the first step. Tempers had run (too) high.
In 1240 Frederick was at the zenith of his power. He considered himself untouchable and acted arrogantly. In the process, he lost sight of reality. To all appearances it seems that around that time the political tide definitely began to turn, and that the good fortune, which he had hitherto known, began to desert him. It didn't seem like that when on August 22 nd of 1241, 'like a gift from Heaven', Pope Gregory suddenly died. The college of cardinals was divided in choosing a successor, and took a year and a half in electing a new pope. On the 25 th of June 1243 cardinal Sinibaldo Fieschi from Genoa was elected the new pope, Innocent IV. The new pope was determined to play a leading role in Europe, and as vicar of Christ to take a position above both the Emperor and the kings of the West. This means that Frederick's relations with subsequent popes were weighed down with a principal problem. Frederick reigned as Roman-German Emperor by the grace of God and considered himself equivalent to the popes. However, the popes invoked their universal right, which reached further than merely ecclesiastical authority, to place themselves above all worldly rulers, including Frederick II. This was the status quo in Western Europe in 1243. Time to return to the Tatars.

An unexpected conclusion: the Tatars withdraw
The Tatar invasion of Europe is occasionally described as a Blitzkrieg: just as fast as the Tatars invaded Europe, they were gone. Why was that? None of the Western powers had proved capable of stopping the Tatars. On the face of it, there does not seem to have been a military reason for the Tatars to withdraw. It gradually became known that on December 11 th of 1241 the Great Khan Ögedei had died in the capital city of the Mongol Empire, Karakorum. He was reportedly poisoned by his sister, the aunt of the future Khan Güyük [10, p. 72]. The entire royal family was expected to return to Mongolia to participate in the election of Ögedei's successor, the Tatar military leader Batu (who was in command of the invasion of the West) included. Batu may have had personal ambitions in the fight for succession, but we cannot be certain. What is certain, however, is that he was the de facto ruler of the westernmost part of the Mongol Empire, and that he eventually proved loyal to Güyük. The Tatar army pulled back through Bulgaria and reached the Black Sea in 1242, leaving a trail of death and destruction in its wake.
The retreat of the Tatar army has been cause for much discussion amongst modern historians over the last decades. Was Great Khan Ögedei's death the real reason for the Tatar withdrawal? Was Batu reluctant to fight in the heavily populated German princedoms, where the weather had a detrimental effect on the Tatar's bows? Or was he simply unwilling to march further because he had accomplished his goal of securing the western border of the Mongol Empire? 21 Denis Sinor (1916Sinor ( -2011, formerly professor of Central Asiatic studies at Indiana University in Bloomington (USA), thinks the Tatar withdrawal is mainly due to logistical reasons. According to Sinor, the size of the Tatar army that invaded Europe should be estimated at 100,000 to 150,000 warriors. Their strength lay in their cavalry, with a seemingly inexhaustible supply of horses. Each warrior had at least three to four horses at his disposal, which meant a total of no less than 400,000 horses were required. This in turn would require 42,000 square kilometres of pasture to feed these horses. This much land was simply not available in Hungary. The Tatar command was in a comparable situation to a commander of a modern armoured division running out of fuel. Going further west, crossing the Danube, would have exacerbated the situation ever more. It was customary for the Tatars to stop the campaigning season in the spring, and let their horses roam free to graze, look for water and procreate, so that they would be ready for war in the fall. According to Sinor this was the reason why the Tatars withdrew from a destroyed and overgrazed Hungary in the spring of 1242; they went looking for steppes for their herds, the basis of Tatar military power [15, p. 31; 17] 22 . Batu subsequently made camp along the river Volga, and not much later founded the city of Saraj Batu, the capital city of the Golden Horde, one of the greatest cities of the medieval world 23 .
Other theories attempting to explain the sudden Tatar withdrawal have been raised. Some historians point to deep divisions between the Tatar military command. Batu had argued with his cousins Güyük and Büri. Güyük and his troops withdrew to Mongolia, where the Great Khan Ögedei flew into a rage and sent him 21 http://www.newworldencyclopedia.org/entry/Mongol_invasion_of_Europe and http://transylvanianhorseman.typepad.com/transylvanian_horseman/2007/10/way-of-the-mo-1.html 22 Pow argues against this, saying that Sinor based his calculations of American horses, and not the Tatar horses, which required far less fodder and which were much hardier. 23 Golden Horde refers to both a Mongol term for the central camp of the Khan and the empire they established. back to Batu to learn some discipline at the latter's hands. Güyük was on his way back to Batu when the news reached him that his father had died, and he turned back again. This means that Batu's withdrawal from the West could have been inspired by the possibility that his enemy was about to be elected the new great khan [10, p. 72]. Oddly enough, the return to the East had been begun before the news of Ögedei's death could possibly have reached the Tatar command in the West. This means he could not have been aware of the imperative to be present for the election of the new great khan. Moreover, Batu repeatedly refused to return to Mongolia [15, p. 16-22].
Other historians point to the substantial losses the Tatars suffered, despite their victory, rendering a further march into the West unsustainable. The Mongol Empire was also plagued by large scale disturbances, caused by the aforementioned Cumans. The problem with this theory is that despite the losses, there was no shortage of warriors, the victories were enormous, and the march had proceeded so quickly that there was no immediate cause to end the triumphal march through Europe [15, p. 41-45].
The historian Peter Jackson, professor emeritus of Medieval history at Keele University in England, raises another, according to him the most straightforward, possibility: the goals that Batu had set for himself could very well have been more limited than what is generally assumed. The suggestion that the Tatars had plans to invade Germany was mainly propagated to the German King Conrad, Frederick II's son, by King Béla of Hungary. It can be assumed that he wanted to use the Tatar threat as leverage to ensure himself of the German king's support. This does not automatically mean that the Tatars in fact intended to occupy these areas permanently. It is possible that the Tatar goal in attacking Hungary was limited to capturing or chasing King Béla out as punishment for his aiding the Cumans, and that after this goal was reached the intention was always to withdraw [10, p. 73-74]. This theory is also disputed. The Tatars intended to conquer a large part of Europe, which is evident from the ultimatum which was delivered to the Emperor Frederick II [10, p. 61]. The attack on the West was part of a greater programme, which was eventually to lead to Tatar rule over the entire world [15, p. 35-41].
More recently another historian, Lindsey Stephen Pow from the Canadian university in Calgary, claimed that in the invasion military concerns were the most prominent reasons for forcing the Tatars to withdraw. Relatively easy targets were still available to them in eastern Europe: the battles of Mohi and Liegnitz took place in largely open terrain, fortifications were weak, sometimes only consisting of earthen walls, society was largely rural and population density and the degree of urbanization were low. The further west the Tatars came, the greater the density of population and degree of urbanization, and the more numerous the defendable fortifications became [15, p. 47] 24 . These fortifications represented an unsurmountable problem for the Tatars, since they lacked manpower and siegeequipment at that moment. Due to strategic reasons, it was impossible for the Tatars to disregard all these fortifications. Western methods of constructing castles, convents, citadels and walled towns had gradually evolved, which lead to great improvement their defensibility. Moreover, most fortifications and towns were 24 Compared to the estimated populations of nineteen million in France and The Low Countries, ten million in Germany and ten million in Italy in the thirteenth century, Hungary was very sparsely populated indeed, with just an estimated two million inhabitants. situated atop mountains, making the task to take them harder still [15, p. 76] 25 . This means the Tatars literally ran into an impenetrable wall, apart from the fact that as nomads, they had little information about these relatively more urbanized regions, although they had a very good intelligence. This explains why the Tatar leaders chose to retreat, instead of staying and inviting the eventual attack [15, p. 46-79].
We will probably never know which theory is correct. The obvious path is to look for a combination of factors, in which logistical and military-strategic reasons prevailed.

In the end
Regardless, the Tatars left Europe as quickly as they invaded it. The Christian West was saved for now, but saw itself facing an existential crisis: instead of trying to liberate the Holy Land by crusades, people were forced to contemplate the defense of their own Christian West. The Christian sense of superiority was confronted by a lack of appreciation of reality and a belated realization of the threat it faced. In the end the Christian West was not saved because of collaboration between papal and imperial forces, but despite a lack thereof. The Tatar invasion mercilessly exposed the divide of Europe at the time. Attention was centered internally, on a vulgar struggle for power between pope and emperor, in which neither seemed willing to compromise. Add to that the underestimation of the danger from outside Europe, partly explained by ignorance, partly by a misplaced sense of European-Christian superiority. The Tatars eventually withdrew. Europe had a lucky escape.