n 1223, Prince Mstislav Svyatoslavich together with his eldest son in a battle with the Tatars at the Kalka River, where his troops led Duke died. Kozelsk passed into the possession of the young son of Prince Mstislav, Basil. However, his reign was very short. When Prince Vasili was 12, in April 1238 the Tatar-Mongol hordes foot on the Chernigovka principalities and came right up to the walls Kozelsk.