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), with he had married around 1371/73. This acquisition, however, wasn't permanent, because later in that year, the Polish King, after finally defeated his uncle, managed to recover this lands. 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. The relations between Władysław II Jagiełło and Janusz I where repaired only in 1387, when the Duke of Warsaw after the election of Władysław II as King of Poland, formally recognized him recognized and then took part in the royal trip to Vilnius, the first step of the Christianization of Lithuania. His good relations with Władysław II where became even more notorious in 1389 during a visit of Vytautas to Masovia, during which Janusz I, in the middle of a feast, declined a golden cup offered to him by Vytautas, which was considered as an insult. 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"). Policy towards the Teutonic Knights The friendly relations between Janusz I and Władysław II Jagiełło caused a permanent state of hostility between Masovia from the Teutonic Order. In 1393, and for unknown reasons, Janusz I was captured during a visit to the border castle in Złotoria near Narew by the komturs of Balga and Ragnit and imprisoned at Malbork Castle by orders of the Grand Master, Konrad von Jungingen. Probably with this actions they wanted to provoke the Polish for war with the Order. As a result of the intervention of Władysław II Jagiełło, who sent deputies to the Teutonic Knights, Janusz I was released. In 1404 the Knights again captured Janusz I, this time with his wife and sons, and kept them in Saxony. Again, only the intervention of the Polish King could release them. In August 1409