Mongol Invasion of Europe (Knightfall)

The Mongol Invasion of Europe, fought sporadically throughout much of the mid-thirteen century, mainly from 1240 to 1247, was one of the largest and most devastating international conflicts the world had ever seen, in both number of nations involved and number of soldiers fielded by both sides. The conflict saw the destruction of the East Slavic principalities, such as Kiev and Vladimir, the invasion and fragmentation of much of eastern and central Europe, and led to the complete destruction and diminishing of many of Europe's strongest regional powers. The first invasions of Europe were largely masterminded by General Subutai and commanded by Batu Khan and Kadan, both grandsons of the Mongolian leader Genghis Khan.

The invasions found new fervor under Ögedei Khan, who approved a renewed invasion in 1242, which would spread into much of the Holy Roman Empire and beyond, causing great financial and infrastructural damage to European cities and societies. During this time the Mongol Empire would siege and successfully occupy for a time the city of Constantinople, collapsing the fledgling Latin Empire after a seven month long siege, albeit with significant Venetian aid. The conflict was not settled until the Treaty of Rome, an all encompassing treaty signed between a coalition of western nations, spearheaded by the Pope in Rome, and the Mongol Empire, which formally recognized the Mongol annexations of parts of the Holy Roman Empire and Eastern Europe, in exchange for a lasting peace. Following the conclusion of this treaty much of the remaining sections of central Europe were placed nominally in a state of tribute to the Mongol Empire, lasting for many years after the war.

Invasions and conquest of Rus' lands
The Russian states first encountered the Mongol horde in 1223, during a period of further fragmentation of the former Kievan Rus'. As detailed by Russian chroniclers of the time, the Mongols were of unknown origin to the locals, and attacked with great ferocity. Word arrived to the princes of the Rus' of the coming Mongol invasion from Cuman nomads, a group of people formally associated with pillaging settlements along the frontier, now known for their peaceful relations. The Cumans appealed to the Rus' states, for assistance against the mysterious threat, although initially their requests went unheeded. It was not until almost a year later, when the Mongols marched along the Dniester River into the Rus, was a response warranted. In response to this threat Mstislav the Bold and Mstislav Romanovich the Old of Kiev both assembled armies and marched eastward to meet the Mongols in battle, at the same time arranging an alliance of Rus' states which also included Yuri II of Vladimir-Suzdal, who promised support for their campaign, and other states.

The Mongols detected the movement of the Rus' army, from the east side of the Dnieper River awaiting re-inforcements from Jochi, Genghis Khan's eldest son, who at the time was undertaking a campaign across the Aral Sea. These re-inforcements, however, did not arrive, as Jochi soon fell ill and was unable to command his army. As the Mongols waited, the Rus' states attempted the trap the Mongols. Forces under the command of the Princes of Galich and Volhynia both were transported south down the river, while the forces of the Princes of Kiev and Chernigov advanced north, planning to attack the Mongols from the rear, supported by an army from Kursk, which attacked from the front. With the Mongols now surrounded, a contingent of ten envoys was sent to the Prince of Kiev, claiming that the Mongols were in the process of leaving Rus' lands, as they had no feud with the Rus' states. In response the Prince of Kiev had the envoys executed, prompting a second contingent of ambassadors to meet with the Rus' to declare war.

The Mongol generals Jebe and Subutai head of the Rus' attempts to entrap them, and marched their army east, away from the enemy force. During this withdraw however, a force of 1000 men under the command of the officer Hamabek stayed behind, to report the movements of the enemy armies. The Rus' forces had no commander-in-chief appointed from among the princes, leaving each army to act independently of each other. Despite the lack of coordination, Mstislav the Bold reached the other side of the river under heavy arrow fire, and he engaged the Mongols, who fought to the very last man after being overwhelmed.

With the Rus' armies now in pursuit of them, the main Mongol army fled for nine days, until they reached the Kalka River. Here the Russian and Mongol forces engaged in close combat, until the Cumans, the Russian allies, were seen fleeing the field of battle, having been led through a gap in the Rus' line by the armies of Volhynia and Kursk. The Mongol cavalry quickly chased into this gap, encountering the confused army of Chernigov, which at that moment advanced into combat before running head on into the retreating Cumans. The army of Chernigov was caught off guard and confused, and the Mongols managed to rout this force, killing their leader Prince Mstislav of Chernigov. This led to mass confusion in the ranks of the Rus' armies, which were then slaughtered by Mongol forces.

As this detachment of the Mongol army cut down the retreating Rus' forces in the center, the Mongol wings closed in on the flanks, shattering the defending lines and cutting off their retreat. Now surrounded by Mongol forces, the defending Rus' armies that still remained were targeted by repeated volleys, and the occasional cavalry charge, devastating the Rus' forces. During this time a small force, led by Mstislav the Bold, managed to cut through the Mongol line and escape, while all else still encased were killed.

Mstislav of Kiev arrived to the field of battle with an army of 10,000 men, and when he saw the current state of the Rus' forces, retreated to his camp, established on a defensive hill by the Dnieper. The Mongols caught up to the remaining Rus' forces and laid siege to Mstislav's camp, who managed to hold out against the attacking Mongols for three days. With his forces heavily depleted, Mstislav of Kiev finally surrendered, on the condition that his forces be allowed to return unharmed to Kiev. Despite this agreement, once the Mongols had secured the enemy camp, the defending army was slaughtered, and Mstislav and a group of nobles were taken prisoner.

The Battle of the Kalka River left the Rus' states heavily weakened and in disarray. After a single engagement, the Rus' had lost a large percentage of their manpower and resources, and were now left vulnerable to a continued invasion deeper into their territory. Out of the many Rus' princes to engage in the battle, only the wounded Daniel of Volhynia and Mstislav the Bold managed to escape the carnage. After the battle Mstislav of Kiev and his nobles were executed in the traditional Mongol fashion reserved for royalty and nobility; without any blood spilled. As such they were buried and suffocated under the victory platform of the celebrating Mongol generals.

The Mongols returned to the east after their victory, where they met with Genghis Khan and the main Mongol army in the steppes east of the Syr Darya River. The achievements of his generals was greatly praised by Genghis Khan, and Jebe and Subutai received great appreciation. The two generals had completed one of history's longest cavalry raids, traveling almost 9000 kilometers in three years, before their eventual return. The Mongol army had also succeeded in placing numerous spies in Rus' territory, which helped to provide frequent reports of activity in Russia and Europe in general. Jebe, however, would die soon after his return, and would not partake in the next phase of the Mongol invasion, in the following decade.

The remaining Rus' forces who had managed to flee the battle were railed under Mstislav the Bold, who managed to reach the western side of the Dnieper. All the boats that Mstislav could find were destroyed, hoping to diminish the Mongol's ability to cross the river and buy himself some time to prepare adequate defenses. Instead the Mongols pursued the Prince of Galich, pillaging towns in the south of the Rus', before turning around. An army of 35,000 horse archers, under the command of Batu Khan and Subutai, next crossed the Volga River, and passed through Volga Bulgaria in autumn of 1236, before being defeated by the Bulgars in an ambush. Despite this initial victory, the Bulgars would be defeated and routed by the Mongols later that year, who then proceeded to attack the Kanglis Cumans, who had supported the Cumans in the Caucasus in their earlier campaigns the year before. Near the Ural Mountains the Cumans were defeated, their Khan having been killed, and they were forced to pay tribute to the Mongols. After a year of fighting, the combined resistance of the Volga Bulgarians, Cumans-Kipchaks, and the Alans was now quelled, and the Mongols turned their attention once more to the Rus' states.

Envoys were sent by Batu Khan to the court of Yuri II of Vladimir, demanding their submission. The Rus' refused, and a month after their demands were sent the Mongols besieged the city of Ryazan, which was annihilated after a six day battle. Yuri II ordered his sons to lead an army and quickly capture the Mongol invaders, but were decisively defeated. The cities of Kolomna and Moscow soon fell, and were burnt down by the Mongols. On 4 February 1238, now completely surrounded by its scorched territory, the city of Vladimir itself was besieged by the Mongols. After only three days the capital fell, and those inside the city were killed in the fires that ensued, which also claimed the lives of the royal family. The Grand Prince himself managed to retreat, fleeing northward over the Volga River. Yuri II quickly assembled an army in Yaroslavl, but was too late to relieve the city of Vladimir. Instead him and his brothers were surrounded by the Mongol forces and annihilated, with Yuri II and Prince Vsevolod of Yaroslavl dying along the Sit River. With their deaths fell the hopes of a unified resistance against the Mongols.

The army of Batu Khan was divided into smaller units, and sent to ransack the cities of Rostov, Uglich, Yaroslavl, Kostroma, Kashin, Ksnyatin, Gorodets, Galich, Pereslavl-Zalessky, Yuriev-Polsky, Dmitrov, Volokolamsk, Tver, and Torzhok. Utilizing Chinese siege engines and other tactics, the Mongols under Tului were able to raze the walls of the defending Russian cities. The most difficult siege and resistance against the Mongols would be the small town of Kozelsk, where the boy prince Vasily, son of Titus, managed to resist the Mongols for seven weeks before falling to hostile forces. Out of all the cities in the Rus', the only major settlements to escape complete destruction were the cities of Novgorod, which the Mongols planned to attack, but unexpectedly turned back for unknown reasons, and the city of Pskov. Of those not killed by the Mongol invaders, many fled into the northeast, hiding in forested regions, along poorer soul between the Upper Volga and Oka Rivers.

Batu Khan returned south, and in the summer of 1238 managed to heavily ransack the Crimea, before pacifying the region of Mordovia. The following winter he sacked Chernigov and Pereyaslav, and finally Kiev, after a large siege, in December 1240. Daniel of Volhynia continued to be a leader of the Russian resistance to invasion, despite losing his principal cities of Halych and Volodymyr-Volynski. The Mongol horde did not leave the Rus' states again until the following year, when they sought to march across Europe. They proceeded to invade Hungary and Poland next, with the goal of reaching the Atlantic Ocean.

First Invasion of Poland
In late 1240 the Mongol force in Europe was divided into three main armies. The first army was placed under the joint command of Baidar, Kadan, and Orda Khan, who begin scouting operations in Poland, while the other two armies marched across the Carpathian mountains and followed the Danube River, respectively. Moving from the recently conquered city of Volodymyr-Volynskyi in the Rus', the first army attacked the Polish city of Lublin, followed by Sandomierz, which fell on 13 February. Central Poland was heavily ravaged by this invading force, which moved under the command of Orda to Wolbórz next, and as far north as Łęczyca, before turning south and heading via Sieradz towards Wrocław. Baidar and Kadan targeted the southern cities of Poland, sacking Chmielnik, Kraków, Bytom, Opole, and Legnica, before exiting Polish lands.

Polish forces under the command of Włodzimierz, voivode of Kraków, were gathered to assemble a defense against the invading force, blocking the road towards Kraków, and concentrating his forces around Miechow. The Mongols, however, did not directly confront the voivode of Kraków, instead towards the city via via Koprzywnica, Wislica and Skalbmierz, before withdrawing to Tursko Wielkie. The Polish forces pursued the Mongols, who fell back to a better defensible position. Meeting finally at the Battle of Tursko, the Polish forces were able to inflict heavy casualties against the Mongols and release some prisoners during the initial clashes. The Polish forces began to loot the Mongol camp, instead of focusing on pursing the Mongol forces themselves, and in when met by a second attack, the Polish forces were destroyed.

Following their success at the Battle of Tursko, the Mongol army split their forces further, with an army under the command of Baidar marching against the city of Kraków in central-south Poland, while the commanders Kadan and Orda Khan advanced in the north. Baidar's forces encountered a Polish army under the command of Włodzimierz, voivode of Kraków, and Pakosław, voivode of Sandomierz, who represented the majority of Polish knights from each of their respective provinces. At the time of this engagement Baidar had previously pursued the forces of Bolesław V the Chaste, Duke of Kraków, who had withdrawn hastily and did not engage in the battle. The flight of the Polish duke damaged the morale of the defending force significantly, and the defense of Włodzimierz and Pakosław was diminished as a result.

Initially the Polish forces managed to hold out against the Mongol attack. Seeing that they could not effectively defeat the Polish forces in direct confrontation, the Mongol army feigned a general retreat, causing the Polish defenders to exit their defenses and pursue the seemingly fleeing force. This advancing army was then bombarded by Mongol reinforcements and decisively defeated. Those Polish soldiers who remained on the battlefield were quickly routed, having suffered heavy casualties. With their last line of defense now shattered, the people of Kraków fell into a panic, and the city was abandoned. When the Mongols entered the city itself they put it to the torch, before pillaging much of the surrounding area.

With the majority of Poland now raided by Mongol forces, the remaining nobility of Poland began to gather their forces, along with Henry II the Pious, Duke of Silesia, around the town of Legnica. In order to buy more time and gather a large force to combat the Mongols, Henry II even abandoned one of his largest cities, Wroclaw, while waiting for his brother-in-law Wenceslaus I of Bohemia, to gather an army and come to his aid. While laying siege to the city of Wroclaw, Baidar and Kadan received word that a large Bohemian army was on its way to relieve the city, and elected to flee from the city without finishing the siege. Instead the Mongol army sought to intercept Henry II before he could meet with this larger force. When the Mongols finally caught up to him, Henry II had been met by the forces of Opole under the command of Duke Mieszko II the Fat, as well as Moravians led by Boleslav, son of the Margrave of Moravia Děpolt III, conscripts from Greater Poland, and volunteer Bavarian miners from Goldberg. The main force of Henry's army included his own personal soldiers from the Silesian Piast duchies, contingents of mercenaries and volunteers, and very small contingents of French Knights Templar and Hospitallers, who together made up the more experienced wing of his army.

The Mongol force gathered at the battle included no more than two tumens from the army of Subutai, who had demonstrated the advantages of horse archers, in terms of tactical mobility and speed when arriving at the field of battle in time. The Mongol strategy essentially consisted of a long series of feigned attacks and fake withdraws, which were intended to draw out the defending force into a more vulnerable position. When dispersed the defending force could be easily run down by Mongol cavalry, or targeted by archers, and as such the Mongols sought to disrupt enemy formations as much as possible, to draw large numbers from the main body of the enemy army. The Mongols' superior training and communication, which relied on a system of flags, made these tactics possible, as it allowed Mongol generals to arrange perfectly orchestrated attacks, and ensured that they had a reliable body of soldiers capable of heeding their commands. In contrast the European knights on the battlefield had virtually no form of communication with supporting forces, and were largely unable to coordinate attacks between groups.

Before the battle Henry II divided his assembled force into four sections, consisting of the Bavarian miners under the command of Boleslav of Moravia, the conscripts from Greater Poland along with some Cracovians led by Sulisław, the brother of the killed palatine of Kraków, the army of Opole under Mieszko, possibly with some Teutonic Knights, and the Silesians, Moravians, Templars and Hospitaller, sunder Henry's personal command. The engagement began when Henry II's Silesian cavalry engaged the vanguard of the Mongol army, and were quickly repelled. Next the cavalry of Greater Poland under the commnand of Sulislaw, and the cavalry of Opole, attacked the Mongol vanguard in succession, causing the Mongols to retreat, drawing away the allied cavalry from the main body of infantry at Henry II's disposal. The Mongol light cavalry then flanked the main Polish lines, hidden under the protection of a smoke screen, which also served to confuse the European forces. While the Mongol light cavalry engaged from the flank, the main cavalry charged against the Polish front lines, supported sporadically by Mongol archers.

At this point the Polish cavalry engaged against the Mongols fell into retreat, and Henry II was forced to call his own reserves and cavalry into battle. In the front the Mongols continued to find renewed success, using their feign tactic to repeatedly draw out the defending force. The European knights on the Polish side were soon detached from the main infantry, and the Mongols were able to separate these two groups and combat them separately as the battle wore on. In the chaos that followed both Henry II and Boleslav of Moravia would be killed in combat, along with the majority of the defending force at the battle. The Mongols also suffered considerable casualties, and were not able to proceed in attacking the main Bohemian army, not yet arrived at the battle.

Upon receiving news of the battle, Wenceslaus I of Bohemia retreated from Poland and returned to Germany, hoping to gather reinforcements from Thuringia and Saxony, but was overtaken by the Mongol vanguard at Kłodzko. Baidar and Kadan were able to pillage much of Silesia, but since their orders were to create a diversion before meeting up with the main Mongolian force, rather than continuing their offensive they marched south, meeting up with Batu and Subutai, who had defeated the Hungarians at the Battle of Mohi.

Mongol Invasion in Germany
Following the defeat of Hungary and its allies at the Battle of Mohi in April 1241, the army of Hungary was largely destroyed, and the nation was seemingly open for pillaging by the invading Mongol forces. Throughout the rest of the year the remaining Hungarian army kept up a mostly successful defense along the Danube river, but that winter the unusually cold temperatures allowed the river to freeze over, allowing the Mongols to cross after a number of minor skirmishes with the defenders. With their defense crumbling, the Hungarian royal family fled to Austria, where they appealed to their ally Duke Frederick II for assistance. Instead Frederick had the Hungarian royals arrested, and extorted them for an enormous ransom in gold, as well as forcing the King of Hungary to cede three western counties to Austria. King Béla and some of his retinue fled to the south-west from Frederick's possession, passing through Hungarian-controlled territory to the Adriatic coast, where they garrisoned at the castle of Trogir.

As the situation worsened across Hungary, and the king himself continued to flee from capture, numerous attempts were made by the Hungarians to reach out to foreign governments in Europe for military assistance. This included messages to the Pope, the Holy Roman Emperor, and the King of France, but at the time none of these nations were interested in military involvement, or greatly underestimated the threat that the Mongols posed. At the same time the Mongols stood within a week's ride of the borders of France, and had the military capabilities to raid numerous settlements across Europe, to many European rulers. With the majority of Hungary now occupied by the Mongols, they set out to appoint a darughachi, and mint coins in the name of the Khagan, despite the ongoing conflict.

Surviving members of the royal family and their allies in central Hungary prepared to continue an active resistance against the Mongol invaders, and large bands of mostly unorganized, irregular armed peasants were employed, who used guerrilla tactics to harass the Mongol army and occasionally engage in open battle. The majority of the civilian population fled the area for neighboring regions less readily accessible to the Mongols, including high mountains in the north and the swamps in the east, often behind older earthwork fortresses consisting of mud-banked encampments on steep natural or man-made hills. As such the Mongols had a difficult time pacifying the region, and rebellions were common.

Invasion of Austria
With the majority of Hungary now pacified by the Mongols, a large force under the command of Batu continued their invasion westward, while a second force entered northern Albania. Immediately Frederick II of Austria gathered his forces in Vienna, preparing to defend against the invaders while help could arrive from elsewhere in the Holy Roman Empire. Frederick however was pressed for allies, as at the time he had a longstanding feud with the Emperor Frederick II and the Hohenstaufen. Frederick II of Austria's harsh rule and frequent wars with his neighbors, especially Hungry, Bavaria, and Bohemia, caused unrest among his citizens, and eventually even the Austrian Kuenringer noble family, which had remained faithful to the Babenbergs, began an insurgency against Frederick's rule upon ascension. During the rebellion led by the emperor's son Henry (VII) against Frederick II of Germany, Frederick von Babenberg appeared to side with the conspirators, in addition to refusing to appear at the 1232 Reichstag diet in Aquileia, and causing frequent fights with King Béla IV of Hungary.

Frederick II von Babenberg's defiance finally reached its peek when in 1235 he refused to attend the diet in Mainz, and Emperor Frederick II officially ostracized him, giving permission to Wenceslaus I of Bohemia to invade Austrian lands. When the Bohemians entered Austria, the city of Vienna opened its gates to the invaders, and turned the city into an imperial free city while the duke continued his ban. It was also there that the emperor had his son Conrad IV elected King of the Romans in 1237. During this time the duke established an Austria rump state at Wiener Neustadt, where he ruled until 1239. At was at this time that the emperor, in need of important allies, arranged for Frederick to end the Bohemian occupation. First the duke promised the engagement of his niece Gertrude of Babenberg to King Wenceslaus' eldest son Margrave Vladislaus of Moravia. Negotiations with the emperor on the elevation of the city of Vienna to a bishopric, and the elevation of Austria, including Stryia, to kingdom, which would have ensured the unity of Frederick's lands in the time to come. These negotiations however never came to fruition, as the emperor required the duke's niece Gertrude now would have to marry himself, who had also recently been banned by Pope Gregory IX. As negotiations continued, it became clear that the duke's niece was unwilling to go through with the marriage, and at the time of the Mongol invasion of Austria, talks were still at a standstill.

In late December 1241 the Mongol army entered Austria and quickly ransacked much of the region around Vienna. Already the winter season and the Duke's recent wars had weakened the city, and the Mongol invasion only served to further weaken the unprepared Austrians. The city of Vienna was surrounded, and Duke Frederick II led his army into battle against the Mongols, hoping to quickly break the siege until help arrived. Frederick's eagerness caused his army to get sucked into a feint by the Mongolian light infantry, and although initially successful, Frederick's army would be cut down in large numbers by Mongolian cavalry and archers once in the open. With his army now in ruin, Frederick fled from the city, running south with his remaining forces. The of Vienna itself soon fell, and those still trapped inside the city were killed.

The Duke of Austria arrived in the city of Wiener Neustadt, where his defenses did not fair much greater. Quickly pursued by the Mongols from Vienna, Frederick was defeated a second time, unable to fully prepare a defense in time. Humiliated, Frederick fled to Graz, but again had little time to prepare an adequate defense. During this time the Mongols managed to sack many of the cities and towns of Upper Vienna, before marching on Graz and pursing Frederick outside the city. Finally the Austrian and Mongol forces met at the Battle of the Drava River. With his back against the river, Frederick was forced to put up a defense against the Mongols, with a force that at this point consisted of very few well trained soldiers. The Austrians were quickly closed in by the Mongols, who found that initially the Austrians were not as readily drawn into combat, as they had become exhausted from marching. The Mongols were forced to launch a direct assault initially, causing heavy casualties, while at the same time drawing out the Austrians and crumbling the defenders in their weakened state. Frederick himself was killed in the battle, effectively marking the end of the ruling House of Babenberg, and sparking conflict over the imperial fiefs of Austria with its neighbors, which greatly expanded the Mongol conflict with the Holy Roman Empire.

At the time of the Mongol invasion, Holy Roman Emperor Frederick II was engulfed in a war in Italy against the Pope, which had drawn away the majority of his forces. After Frederick II, Duke of Austria had been quelled in 1237, and the emperor had his son Conrad proclaimed King of the Romans, the emperor was able to divert his entire force to Lombardy to deal with hostile forces in Italy. Negotiations between the imperial forces, the Lombard cities, and the Pope soon broke down, and Frederick invaded Lomnbardy from Verona, where in November 1237 he won a decisive victory against the Lombard League at the Battle of Cortenuova. Frederick held a large triumph in celebration at Cremona, in the manner of an ancient Roman emperor, complete with the captured carroccio of the enemy and an elephant. Requests for peace were rejected, including large sums of money in exchange for peace form Milan. Instead Frederick demanded total surrender, which provoked further resistance from Milan, Brescia, Bologna, and Piacenza. At the Siege of Brescia Frederick was forced to withdraw, at the same time preventing attempts by the Lombards to capture him.

In early 1239 Gregory IX excommunicated the emperor while he held court in Padua, and in response the emperor expelled the Franciscans and Dominicians from Lombardy, and elected his son Enzo as Imperial vicar for Northern Italy. The Duchy of Spoleto, Romagna, and Marche, all nominally territory of the Papal States, was seized by Enzo, while Fredrick announced his intentions to destroy the Republic of Venice after they had sent a small fleet of ships against him in Sicily. Frederick next marched into Tuscany, where he marched in triumph through the streets of Foligno and Viterbo, before finally determining to march against Rome and restore the ancient empire that had once governed over the entire region. After a long siege at Rome Frederick proved unsuccessful, and broke his siege to return south. Peace negotiations were inconclusive, and the emperor sacked the papal possession of Benevento as he marched south.

After the fall of Ferrara, Frederick returned to the north of Italy and captured Ravenna, followed by the city of Faenza following another long siege. Attempts by the Pope to call a resolving council for the matter failed, and at the Battle of Meloria cardinals and church officials en route to Rome from Genoa were captured by Pisa. Again Frederick attacked the city of Rome directly, leaving behind much of Umbria in ruin, including the city of Grottaferrata. Pope Gregory IX died on 22 August 1241, and Frederick purposely withdrew his forces as a sign that his feud extended only against the previous pope, not against the church itself. The already established relationship between the papacy and the empire remained cold however, and a back and force conflict ensued into 1242.

Austrian Succession War
The sudden death of Frederick II, Duke of Austria at the Battle of the Drava River left the Duchy of Austria without a ruler, and several claimants rose to claim the throne. Each of these claims however was largely dependent on these neighboring rulers’ abilities to repel the Mongols and secure Austria by force, something not easily done. Wenceslaus I of Bohemia sought to place his son Vladislaus, Margrave of Moravia on the throne of Austria, ensuring that Bohemia and Austria would be united under the Přemyslid dynasty. Wenceslaus arranged for his son to marry Frederick’s daughter Gertrude, the last heir of the Babenbergs, who according to the Privilegium Minus was next in line to inherit the throne.

The Mongols left Vienna and Upper Austria in devastation, prepared to continue their conquests to neighboring regions. With the Bohemians now preparing their forces for an invasion into Austria to secure the duchy for the Přemyslid dynasty, an army under the command of Baidar split off from the main group to retaliate against the Bohemians to the north. The Mongols came to the Thaya River, where forces under the command of Vladislaus awaited them on the opposing bank. Armed with a large army from Bohemia, his remaining personal forces from Moravia, which largely conisted of armed peasants, and contingents from Silesia and other states, Vladislaus initially outnumbered the Mongols, however the Mongols were able to stall combat and wait for the remainder of their forces to arrive.

Imperial Retaliation
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Guns' Version:

Following the swift collapse of Eastern Europe- a process that only took a few months- the Holy Roman Emperor, Fredrick II, finally decided to act, turning his army away from Rome and marching swiftly upwards, expecting to meet the Mongols at the tiny town of Nitra, where the surrounding terrain would provide an effective foil for the Mongol cavalry. However, his estimates of how long it would take the Mongols to push forward were widely off; Nitra fell before Fredrick's army had even left Italy, and the Mongol hordes poured into the region, seizing several towns and brutally putting the defending army down at Bratislava, before progressing without pause into a headlong charge towards Vienna.

Again, Fredrick and his armies were too slow, and Vienna fell as they were just two days away. Feeling the situation slipping away from him - and fearful for Prague, the capital of the HRE - Fredrick took his army and made a stand at the city of Brno, where he finally met the Mongols in open combat.

Reinforced by nearly 7000 troops from Bohemia, with another 4000 on their way, Fredrick was confident that he and his armies could successfully stop the horde in its tracks. However, on the day of the battle, he made several crucial mistakes. Firstly, he placed his army such that the Mongols would have to fight him to take Brno- they could not go around- but in doing so, he overstretched his center, assuming that in the case of an all out Mongol attack on his center, he could fold in the wings, thus entrapping them. Secondly, he wildly underestimated the number of Mongols and their auxiliaries fighting, assuming that the force the Mongols could field was no more than 10,000, when in fact- counting auxiliaries and conscripts - it was closer to 70,000, actually outnumbering Fredrick's troops by approximately 15,000 soldiers. Lastly, rather than taking up defensive positions around the city, he instead placed his cavalry several miles from the city, and placed his infantry in a shield wall, hoping to crush the Mongols with his cavalry against his infantry wall.

Come the day of battle, these mistakes quickly began to play out. The Mongols hurled their auxiliaries- nearly 20,000 troops- against the German left wing, immediately tipping off the Germans that something was extremely wrong. The Germans held the position throughout the morning, and managed to drive back the Mongols for a short period using point-blank crossbow firing and infantry charges. However, the battle took a brutal toll on the left wing, and by noon Fredrick was forced to send over 5000 troops to reinforce the flank, leaving his center with just under 10,000.

The Mongol attack on the left wing, however, was only the start. In the afternoon, the Mongols began raining down arrows on the German right flank, causing many casualties, and then launched an attack against the flank, using over 40,000 troops, vastly outnumbering the Germans there and threatening to surround Fredrick's troops. Unwilling to deplete his center further, Fredrick ordered the right wing to retreat back towards Brno, ensuring that the Mongols could not surround the German troops at the cost of opening up the center's flank for attack. Fredrick, still unwilling to retreat, now called in his cavalry charge- far too late. The cavalry drove back the Mongols on the German left wing, but failed to destroy that force, and Batu Khan, commanding the Mongols, ordered in his reserve, 10,000 troops, which surrounded the cavalry and massacred them. The left flank, now exposed and taking severe casualties, routed and fled the battle, running up north. Fredrick, seeing the collapse of the left flank and knowing this made his position untenable, decided to retreat as well before the Mongols could attack his center. The right wing, commanded by Fredrick's son William, was left completely surrounded, and was forced to fight nearly to the last man. William, ironically, survived the battle, was captured trying to flee, and was executed not long after by the Mongols.