Siemovit II of Masovia (Premyslid Bohemia)

Siemovit II of Masovia was born to Boleslaus II and his first wife Sophie in 1283 and became duke in 1313, he was duke ruled by another duke, son of Wenceslaus III, Vladislaus of Warsaw. He hated this and in March, 1348 started anti-premyslid rebelion while Vladislaus and John the Blind on side of Philip VI of France, his rebelion was however crushed and he was killed.