Battle of the Stugna River

The Battle of the Stugna River (26 May 1093) was fought between the princes of Kievan Rus', Sviatopolk II of Kiev, Vladimir Monomakh of Chernigov, and Rostislav Vsevolodovich of Pereyaslavl against the nomadic Cumans. The Kievan forces were defeated.
Background.
The Cumans raided Rus' soon after the death of Vsevolod and sought to buy peace with the new great prince, Sviatopolk. However Sviatopolk incarcerated the Cumans' ambassadors, and the Cumans came in force to attack Kiev. Facing an enemy army of eight thousand, Sviatopolk took the advice of counsel and called for help from Vladimir Monomakh, prince of Chernigov. Vladimir came with his troops and also called upon his only brother, Rostislav of Pereyaslav.
Battle.
A union of Kievan princes against Cumans was achieved, and Sviatopolk released the ambassadors of Cumans. The troops of the three princes joined together and set out for the city of Trepol'. Approaching the Stugna River, the princes were undecided, so they stopped to have a council, while the Cumans were across the river facing them. Vladimir, whose wife was a Cuman princess, continued to demand that they sue for peace, but the Kievan troops wanted battle. They crossed the river and met the Cumans in a valley at the rampart of Trepol'. Sviatopolk deployed on the right, Rostislav in the center, and Vladimir on the left. 
As the Kievan troops reached the rampart, the Cumans bowmen attacked Sviatapolk's men, and after a bloody engagement his troops broke. Sviatapolk attempted to make a stand, but the impact of his retreating men carried him back. Then Vladimir's force was attacked and after a fierce confrontation all the Kievan troops were retreating. Sviatapolk took cover in Trepol', but Rostislav and Vladimir attempted to swim the Stugna River. Rostislav, in heavy chain armour, drowned. Vladimir retreated to Chernigov and Sviatapolk retreated at night to Kiev.
The Kievan-Pechersky Paterick ascribed Rostislav's death to his own haughtiness. It is said that he refused to enter the church and pray for the battle's outcome. The young prince's death is also recalled in the "Tale of Igor's Campaign":