Janusz I the Old

As the result of the partition of Masovia between him and his younger brother Siemowit IV after the death of their father on 16 June 1381, Janusz I finally obtain the totally of his domains: Warsaw, Nur, Łomża, Liw, Ciechanów, Wyszogród and Zakroczym.

In this area, Janusz I faithfully maintained a close cooperation with the successive Polish rulers: Louis of Anjou, Jadwiga and Władysław II Jagiełło.

In this way, Janusz I was directly opposed to the policy of his brother Siemowit IV, who tried to take advantage of the difficulties in the Angevin dynasty and wanted to obtain the Polish crown for himself.

The preference for the Polish interests in Władysław II Jagiełło in detriment of the Grand Duchy of Lithuania caused a civil war between him and his uncle Kęstutis.

Janusz I took advantage of this situation in 1382 to capture the towns of Podlachia and Drohiczyn, claiming them as a part of the dowry of his wife Danutė (a daughter of Kęstutis),[2] with he had married around 1371/73.

Janusz I, not wanting to further complicated the situation, received with extreme coldness the fugitive Vytautas, despite being his brother-in-law, and after his refusal to accept baptism sent him to the Teutonic Knights.

On 2 September 1391 Władysław II Jagiełło formally gave Janusz I the previously disputed lands of Podlachia and Drohiczyn in perpetuity, and with them he also received the towns of Mielnik, Bielsk Podlaski and Suraż ("terram nostram Drohiczensen, Melnyk, Surasz, Byelsko ac omnibus villis in eisdem districtubus").

[3] Between 1409-1411 Janusz I continued his support to Władysław II Jagiełło in the great war against the Teutonic Order and fielded a banner of cavalry[4] to aid the Polish King.