Battle of Pobiedziska

It ended with a decisive Polish victory and the destruction of Miecław's army and led to the signing of the truce between both sides, which lasted until 1047.

[4] 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.

Expecting the attack from Rus', Miecław had formed an alliance with Pomeranian and Yotvingian tribes.

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.