Battle of 1047 between Casimir I and Miecław

[5] Seizing the opportunity, around 1038, the cup-bearer Miecław had formed the state in Masovia, declaring its independence from Poland, and started his own royal dynasty.

[1] He had formed an alliance with Yaroslav the Wise, Grand Prince of Kiev, the leader of Kievan Rus', via the marriage of Maria Dobroniega with Casimir.

The battle ended with a decisive Polish victory and destruction of Miecław's army and led to the signing of the truce between both sides.

[3][4] The location of the battle remains unknown in modern times, though it was known to the 11th-century historian, Gallus Anonymus, according to whom, it took place near the river, with the bluff edge.

[3] However, according to Wincenty Kadłubek in his Chronica seu originale regum et principum Poloniae, he had escaped to Prussia, where he was murdered.