Siemowit II of Masovia

Siemowit II of Rawa (pl: Siemowit II rawski; 1283 – 18 February 1345), was a Polish prince member of the House of Piast, Duke of Warsaw and Liw during 1310-1313, after a new division with his brothers since 1313 ruler over Rawa Mazowiecka, Sochaczew, Zakroczym, Gostynin, Ciechanów and Wizna, regent of Płock during 1336–1340.

He was the eldest son of Bolesław II of Płock and his first wife Gaudemantė (Sophia), the daughter of Grand Duke Traidenis of Lithuania. He was probably named after his paternal grandfather, Siemowit I.

Before his father died, in 1310 Siemowit II received the districts of Warsaw and Liw. When Bolesław II died in 1313, the Duchy of Masovia was divided. As the oldest son, Siemowit II obtained the central part of Masovia, with Rawa Mazowiecka as his capital. His younger brothers Trojden I and Wenceslaus were respectively given Czersk and Płock. This division didn't satisfy anybody and lead to a brief war between the three brothers in 1316. Apart from a brief mention in the Roczniku miechowskim, the exact details of this conflict are unknown.

In terms of foreign policy, Siemowit II tried to skillfully maneuver between his powerful neighbors: Władysław I the Elbow-high, the Teutonic Order, Lithuania and Bohemia. This policy was expressed, inter alia, in frequent changes of alliances.

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