Background
He was the seventh son of Bolesław IV of Warsaw and Barbara Olelkovna of Slutsk-Kapy, a Lithuanian princess, (granddaughter of Vladimir Olgerdovich).
He was the seventh son of Bolesław IV of Warsaw and Barbara Olelkovna of Slutsk-Kapy, a Lithuanian princess, (granddaughter of Vladimir Olgerdovich).
In 1484 he abdicated his rule over Błonie, Tarczyn, Kamieniec and Zakroczym. In the division of the paternal domains, he received Warsaw, Nur and Liw. The King, however, had other plans, and finally Masovian Piasts had to abandon their ambitious plans.
The conflict for Sochaczew caused a temporary coolness in the relations between Bolesław V and the Polish Kingdom, which was expressed in his neutrality during the dispute between Nicolaus von Tüngen and King Casimir IV for the Bishopric of Warmia.
On 20 July 1477 Bolesław V married with Anna, a daughter of Zygmunt of Radzanów, Chorąży of Płock and Voivode of Belz. The union, however, due to the low origins of the bride, was morganatic, thus any children from the marriage had rights of inheritance.
They had no children. Foreign unknown reasons, in 1484 Bolesław V resigned to the brothers parts of his domains: Konrad III received Zakroczym and Janusz II obtain Kamieniec, Błonie and Tarczyn.
Bolesław V died on 27 April 1488 and was buried in Warsaw.