In November and December of 1240, the Mongols placed a siege of the city of Kiev as part of the invasion of Rus. This ended in a decisive Mongol victory, and devastating blow to the Rus armies, especially as this conquest allowed the Mongols to expand westward into Europe.
In 1237, the Mongols, under the ruler Batu and his cousin Mongke, began their invasion of the Rus by conquering the northern principalities of Ryazan and Vladimir-Suzdal. In 1239, they advanced against southern Rus, capturing the cities of Pereyaslav and Chernihiv.
The next year, the Mongol general Batu Khan reached Kiev. At the time, the city was ruled by the principality of Halych-Volhynia, with only a thousand defenders inside the city. When the Mongols attacked, the chief commander of Kiev, Dmytro, voivode of Danylo of Halych was away in Hungary seeking a military union to prevent invasion.
When the Mongols approached Kiev, Möngke was so impressed by the splendor of the city that he offered terms for surrender. Kiev refused, killing the Mongol envoys. Mongke retaliated with violence, assaulting the city and crushing the Rus vassals who came to relieve Kiev with Dmytro. The Mongols then camped outside the city gates, setting up catapults for bombardment. After only 8 days, the Mongols breached the walls of Kiev, engaging in hand-to-hand combat with the city’s inhabitants, and wounding their leader Dmytro.
That night, the Mongols retained their offensive in the city, and the Kievans fled to the center of the city. So many people reportedly gathered in the Church of the Tithes that the church balcony collapsed from the weight, crushing many. The Mongols continued to attack the city, massacring its population, burning its buildings, and looting its wealth.
After this decisive victory, the Mongols were in perfect position to advance into Poland and Eastern Europe.
A model of Kiev in the 10th-13th centuries by Ukrainian artist D. Mazyukevich.