Sack of Chernigov

Sack of Chernigov was part of the Mongol invasion of Rus.'
Prelude.
Mongol invasion of Rus can be divided into two phases. In winter of 1237-38 they conquered Northern Russia (principalities of Ryazan and Vladimir-Suzdal) with the exception of Novgorod, but in spring of 1238 retreated back to Wild Fields. The second campaign, aimed to Southern Russia (principalities of Chernigov and Kiev) came in 1239.
Battle.
In the autumn of 1239, the Tatar horde captured Hlukhiv, Kursk, Rylsk, and Putivl, and advanced towards Chernihiv. When Prince Mstislav heard that the Tatars were attacking the town, he came with his troops to confront them. The nomads used catapults that hurled stones the distance of a bowshot and a half. Mstislav barely escaped, but many of his men were killed.
Aftermath.
After Chernihiv fell on October 18, the Tatars pillaged the towns in the surrounding countryside. Even the capital city of Kiev fell in autumn of 1240.