Mongol light reconnaissance units, led by Orda Khan, pillaged through Meissen and burned most of the city of Meissen to the ground. The Chronica sancti Pantaleonis records these attacks. Invasion of Austria The subjugation of Hungary opened a pathway for the Mongol Horde to invade Vienna. Using similar tactics during their campaigns in previous Eastern and Central European countries, the Mongols first launched small squadrons to attack isolated settlements in the outskirts of Vienna in an attempt to instill fear and panic among the populace. In 1241 the Mongols raided Wiener Neustadt and its neighboring districts, located south of Vienna. Wiener Neustadt took the brunt of the attack and, like previous invasions, the Mongols committed horrible atrocities on the relatively unarmed populace. The city of Korneuburg, just north of Vienna, was also pillaged and destroyed. The Duke of Austria, Frederick II, had previously engaged the Mongols in Olomouc and in the initial stages of the Battle of Mohi. Unlike in Hungary however, Vienna under the leadership of Duke Frederick and his knights, together with their foreign allies, managed to rally quicker and annihilate the small Mongolian squadron. After the battle, the Duke estimated that the Mongols lost 300 to upwards of 700 men, while the defending Europeans lost 100. Austrian knights also subsequently defeated the Mongols at the borders of the River March in the district of Theben. After the failed initial raids, the rest of the Mongols retreated after learning of the Great Khan Ögedei's death. Invasion of Bulgaria During his withdrawal from Hungary back into Ruthenia, part of Batu Khan's army invaded Bulgaria. A Mongolian force was defeated by the Bulgarian army under Tsar Ivan Asen II. A larger force returned to raid Bulgaria again the same year, though little is known of what happened. According to the Persian historian Rashid-al-Din Hamadani, the Bulgarian capital of Tarnovo was sacked. This is unlikely, but rumor of it spread widely, being repeated in Palestine by Bar Hebraeus. The invasion of Bulgaria is mentioned in other contemporary sources, such as Philippe Mouskès, Thomas of Cantimpré and Ricoldo of Montecroce. Contemporary documents indicate that by 1253, Kaliman I was a tribute-paying vassal of the Mongols, a status he had probably been forced to accept during the invasion of 1242. European tactics against Mongols The traditional European method of warfare of melee combat between knights ended in catastrophe when it was deployed against