prince Janos I "The Older" Piast of Masovia

public profile

Is your surname Piast of Masovia?

Research the Piast of Masovia family

prince Janos I "The Older" Piast of Masovia's Geni Profile

Share your family tree and photos with the people you know and love

  • Build your family tree online
  • Share photos and videos
  • Smart Matching™ technology
  • Free!

prince Janos I "The Older" Piast of Masovia

Lithuanian: kun. Jonušas "Vyresnysis" Piastas Mazovietis, I, Polish: książę Janusz I Starszy Piast-Mazowiecki
Birthplace: Wyszogrod, Warszawa, Mazowia, Poland
Death: December 08, 1429 (76-85)
Place of Burial: Basilica of St. George's Arch. John the Baptist in Warsaw
Immediate Family:

Son of Książę Siemowit III "Starszy" Prince of Mazovia and Euphemia von Troppau
Husband of princess Danute of Lithuania
Father of Olga Piast-Mazowiecka, Princess; Janus "Junior" Piast-Mazowiecki, Prince; prince Boleslaus Piast of Masovia and Konrad Janusovich Piast-Mazowiecki, Prince
Brother of Anna; Eufemija Siemovitaitė; Siemowit IV, duke of Masovia and Margaret of Masovia
Half brother of NN; NN and Henrik of Mazovia

Occupation: ruler of Warsaw-Masovia / Mozūrų kunigaikštis
Managed by: Dag Henrik Gösta Lundqvist
Last Updated:

About prince Janos I "The Older" Piast of Masovia

Janusz I Starszy (warszawski) – od 1373/1374 r. książę warszawski, od 1381 r. w wyniku podziału książę na Warszawie, Nurze, Łomży, Liwie, Ciechanowie, Wyszogrodzie i Zakroczymiu, lennik Polski, od 1391 na Podlasiu (dożywotnio).

Janusz I (c. 1340 – 1429) was Duke of Warsaw (from 1373), one of the dukes of Masovia after its division amongst the sons of Duke Siemowit III.

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. In 1376 he married princess Danutė (Danuta Anna), 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 1386 Janusz became a hereditary vassal of Poland. In 1391 he inherited the title of the Duke of Podlachia. In 1406 he moved the capital of Masovia from Czersk to Warsaw. In 1409 he organised a banner of cavalrymen 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.

With Danuta, he fathered three sons: Janusz Młodszy (Janusz the Younger), Bolesław Januszowic and Konrad Januszowic. He outlived them all, and passed his territories to his grandson, Bolesław IV of Warsaw.

view all

prince Janos I "The Older" Piast of Masovia's Timeline