From an Enemy to a Loyal Ally, or the Relationship between Siemowit IV, Duke of Masovia, with Jadwiga of Capetian House of Anjou and Władysław Jagiełło

After the death of king Louis I of Hungary in 1382 an almost two years long interregnum started in the Kingdom of Poland. One of the most important candidates to the Polish crown was Siemowit IV, Masovian duke of Rawa and Płock. In the Polish nationwide convention of knights and dignitaries in Sieradz which took place 28 March 1383 he was even proclaimed to be the king of Poland, but the coronation finally did not happen. Afterwards duke Siemowit IV was attempting to rule the kingdom of Poland, but he did not succeeded, and it was Jadwiga of Capetian House of Anjou, and later Władysław Jagiełło who came into power. Siemowit IV became their vassal, although he simultaneously pursued independent policy, often cooperating with the authorities of the Teutonic Order. Trying to keep the independence of his duchy Siemowit IV was forced to seek for a balance between powerful neighbours, inevitably heading for military confrontation.