Miecław (; 10th/11th century – 1047) was a cup-bearer of king Mieszko II Lambert, who in c. 1038 had proclaimed independence of the state that he ruled, from the Duchy of Poland, beginning the rebellion that lasted until his death in 1047.
History
thumb|left|220px|The [[Duchy of Poland (1031–1076)|Duchy of Poland in 1037, including the borders of Miecław's State.]]
Following the death of Mieszko II Lambert, king of Poland, in 1034, and the exile of his son, Casimir I the Restorer, to Kingdom of Hungary, the state had fallen into a period of destabilization within the Duchy of Poland, that led to the start of the 1038 Peasant Uprising. 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.
Casimir I the Restorer, duke of Poland, had returned to the country from his exile in 1039. Miecław's forces had fought with the army led by Casimir and Yaroslav, in the battle of Pobiedziska. 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.
The fighting had begun again in 1047, as Casimir I, together with Yaroslav, had organized the attack on Masovia, which led to the battle of their forces against the forces of Miecław and Pomerelia. 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. According to him, Miecław forces had 30 divisions of cavalry, while Casimir, 3 divisions. It is probable that he did not account for the forces of Yaroslav the Wise, and that both sides, in fact, had a similar number of forces.