12 Military Deceptions that Changed the Course of History Forever

On May 31, 1223, during the Mongol invasion of the Cumans at the Battle of the Kalka River, the Mongol armies of Genghis Khan led by Subutai and Jebe defeated the Kievan Rus and Cumans. From the article:

"Battle of the Kalka River
The Battle of Kalka River on May 31st, 1223, occurred at the tail end of one of history’s longest feigned retreats, in which a Mongol army led by two of Genghis Khan’s chief lieutenants, Subutai and Jebe, lured a much larger force of Russians and Cumans into chasing them across the Steppe for hundreds of miles, before the Mongols turned around and annihilated their pursuers.

Following Genghis Khan’s conquest of the Khwarezmian Empire, Mongol generals Subutai and Jebe, who had chased the defeated empire’s ruler to his death in an island on the Caspian Sea, got permission from Genghis to conduct a reconnaissance in force westwards, and with their force of 20,000 Mongols, raid into Iran, then northwards into the Caucasus, before returning to Mongolia via the Steppe north of the Caspian Sea.

En route, the duo met and defeated the nomadic Cumans, whose khan fled to the Kievan Rus and convinced them to help fight the Mongols. The Rus and surviving Cumans assembled an army of 80,000 men under the joint command of Mstislav III of Kiev, and Mstislav the Bold of Galich. They caught up with and defeated the Mongol rearguard, at which point Jebe and Subutai decided to lure their pursuers into an ambush.

Pretending to panic after their rearguard’s defeat, the Mongols conducted a feigned retreat, and the led their pursuers on a merry chase which lasted for nine days, during which their pursuers lost their cohesion and became strung out in a long column. Finally, on the 9th day, Subutai and Jebe set up an ambush, crossing the Kalka River and concealing their forces near the opposite bank.

When the pursuers began crossing the river, the Mongols waited until most had reached their side, before springing their ambush and charging suddenly out of their concealed positions to shower the Russians with a rain of arrows before closing in. The ferocious and sudden attack from an enemy whom they had thought was in panicked flight shocked the Russians and threw them into confusion, which swiftly turned into a rout.

The Mongols encircled their panicked opponents and butchered them, killing around 75,000 out of the 80,000 who had set out to pursue them. Of the defeated commanders, Mstislav the Bold escaped, while Mstislav of Kiev managed to reach a fortified camp on the Dnieper, where the Mongols surrounded him. He eventually surrendered in exchange for a promise of safe conduct back to his territory, but the Mongols reneged, slaughtered his men, and executed him."