Janusz I of Warsaw

Who was Janusz I of Warsaw?

Janusz I was Duke of Warsaw, one of the dukes of Masovia after its division amongst the sons of Duke Siemowit III known as Janusz I the Elder.

Among the lands in his domain were the areas of Warsaw, Nur, Łomża, Ciechanów and Różan. In 1374 he inherited Zakroczym and in 1381 the lands of Czersk, Liw and Wyszogród as the result of partition of Masovia between his younger brother Siemowit IV and himself. In 1376 he married princess Danutė, daughter of Lithuanian Duke Kęstutis. Because of his family ties, he served as a mediator between king of Poland Jogaila and the Grand Duke of Lithuania Vytautas.

In 1381 duke Janusz paid homage to new king of Poland Louis I of Hungary, and in 1386 he became a hereditary vassal of Poland. In 1391 king-consort Jagiello awarded duke Januszthe the disputed lands of Podlasie for life of duke Janusz. In 1406 he moved the capital of Masovia from Czersk to newly developing strategic town of Warsaw and actively worked to develop his towns, fortified his castles and strongholds. In 1409 he fielded a banner of cavalry to aid his liege, the king of Poland, in the war against the Teutonic Order. The following year together with his banner, despite his age, he took part in the Battle of Grunwald. His banner had in its badge a quartered field,intwo quarters a white eagle in a red field and the other two quarters had a winged dragon in a white field.