Siemowit (or Ziemowit) II of Masovia (1283 – 18 February 1345[1]) was Duke of Masovia from 1310 to 1345. He was a member of the House of Piast. Siemowit was Duke of Warsaw and Liw (1310–1313). In 1313, he became the ruler of Duchy of Rawa. He was regent of Płock (1336–1340).
Siemowit was the eldest son of Boleslaus II of Masovia and his first wife Sophie, the daughter of Grand Duke Traidenis of Lithuania.
Before his father died, Siemowit received the small regions of Warsaw and Liw. When his father died in 1313, Masovia was divided. As the oldest son Siemowit obtained the central part of Masovia, with Rawa Mazowiecka (capital) Sochaczew, Zakroczym, Gostynin, Ciechanów and Wizna. His younger brothers Trojden and Wenceslaus were respectively given Czersk and Płock. This division did not satisfy anybody and lead to a brief war between the three brothers in 1316.
In terms of foreign policy, Siemowit tried to maneuver between his powerful neighbors: Poland, Teutonic Order, Lithuania and Bohemia. At first Siemowit and his brothers supported Ladislaus the Short.
In 1326 at Brodnica the brothers changed otheir political line and entered an alliance with the Teutonic Knights which guaranteed them not to touch their territory and independence. In retaliation, Ladislaus and Lithuania launched an attack against Masovia. Poland stayed away but the Teutonic Order and Bohemia became involved.
In 1329 Siemowit changed sides and joined forces with Ladislaus the Short. After this betrayal, an army of Teutonic and Czechs invaded the Duchy of Płock and forced Siemowit's brother Wenceslaus to pay vassalage to John of Bohemia, a candidate for the throne of Poland. In fear of suffering the fate as their brother, Siemowit and Trojden remained aloof from the conflict between Poland and Teutonic. In 1333 The Teutonic offered Siemowit Brześć Kujawski, they took it to Poland in exchange for a new alliance. The Duke of Rawa declined the offer and but it definitely fitted the part of Ladislaus the Short.
In 1343 the conclusion of peace "eternal" between Poland and the Teutonic Order relieved Siemowit II whose duchy had an uncomfortable situation between the two powers. As a potential successor Casimir III the Great on the throne of Poland, Siemowit II agreed to waive the rights of Chełmno and Eastern Pomerania.
Siemowit II died in Rawa on February 19, 1345 at his property Sochaczew. He is buried in the Cathedral Płock. He never married and left no descendants. His duchy was divided among his three nephews: Boleslaw III of Płock, Siemowit III of Masovia and Casimir I of Warsaw[2].
| Preceded by Boleslaus II |
Duke of Masovia 1310–1345 |
Succeeded by Casimir I of Warsaw |