The Battle of Mohi, or Battle of the Sajó River, (April 11, 1241) was the main battle between the Mongols led by Batû-Khan, grandson of Genghis Khan in the Kingdom of Hungary during the Mongol invasion of Europe.
Just before dawn the Hungarian defenders found themselves subjected to a hail of arrows and stones, “accompanied by thunder and flashes of fire. Some historians have claimed that on this occasion the Mongols would have used the first cannons in European history. However, it is more likely that it was only catapults and ballistae, combined with Chinese firecrackers, that inspired this terror. Anyway, this was the Mongolian version of a modern artillery preparation. This Mongol bombardment was soon followed by a violent assault.
Stunned by the sound and violence of the attack, the defenders are quickly overwhelmed, and the Mongols stream across the bridge. Alerted, Bela's army rushes out of its fortified camp. It quickly becomes clear, however, that this is just a fixation attack.
The main effort is indeed led by three tümens (about 30,000 men), perhaps placed under the direct command of Subotai. Taking advantage of the shadows of dawn, these warriors crossed the cold waters of the Sajo, south of the bridgehead, then turned north to strike at the right flank and rear of the Hungarians. Unable to resist this devastating charge, the defenders took refuge in their camp. At 7 am the latter was completely taken over by the Mongols. This is followed by several hours of bombardment with stones, arrows and burning naphtha.
It then seems to some Hungarians that a way of salvation exists in the east. A small group begins to gallop towards freedom. As the Mongol assault escalates, men flee. Soon a stream of men goes west. Everyone tries to flee to save their skin. Many fugitives throw down their weapons in order to run faster. Unfortunately for them, they fell into a trap set by the Mongols. Mounted on fresh horses, the Mongols appear on all sides, mowing down the exhausted men, hunting them down in the swamps, and storming the villages in which some have sought refuge. In a few hours of horrible butchery, the Hungarian army was totally destroyed, leaving between 40,000 and 70,000 dead.
King Béla IV, however, barely manages to escape. With him, he only has three of his men left. Taking advantage of the Hungarian collapse and the flight of their sovereign, the Mongols stormed the city of Pest, which remained without defenders. As usual, the conquerors set out to burn the city and massacre the population.
This victory assures the Mongols control of the lands from the Dnieper to the Oder and from the Baltic to the Danube. In four months the Mongols defeated Christian armies totaling five times their strength.