Casimir I of Warsaw (pl: ''Kazimierz I warszawski''; 1329/31 – 26 November/5 December 1355Janusz Grabowski: ''Dynastia Piastów mazowieckich'', Kraków 2012, p. 444.), was a Polish prince, member of the

House of Piast The House of Piast was the first historical ruling dynasty of Poland. The first documented List of Polish monarchs, Polish monarch was Duke Mieszko I of Poland, Mieszko I (–992). The Poland during the Piast dynasty, Piasts' royal rule in Pol ...

, Duke of

Czersk Czersk (; ; formerly , (1942-5): ) is a town in northern Poland in Chojnice County, Pomeranian Voivodeship. As of December 2021, the town has a population of 9,844. Today the center of the city of Czersk in is the Village Square. The infrastructu ...

1341–1349 jointly with his brother, after 1345 ruler over

Rawa Mazowiecka Rawa Mazowiecka is a town in central Poland, with 16,090 inhabitants (2022). It lies in the Łódź Voivodeship and is the capital of the Rawa County. From 1562 the city hosted the ''Rawa Treasury'' for the Military of the Polish–Lithuanian Com ...

jointly with his brother, after 1349 sole ruler over Warsaw, after 1351 sole ruler over

Sochaczew Sochaczew () is a town in central Poland, with 33,456 inhabitants (as of 2023). In the Masovian Voivodeship (since 1999), formerly in Skierniewice Voivodeship (1975–1998). It is the capital of Sochaczew County and is located approximately west ...

, Polish vassal since 1351. He was the third and youngest son of Trojden I of Czersk and Maria, daughter of Yuri I, King of Halych-Volhynia.

Life

After the death of his father in 1341, Casimir I ruled jointly with his oldest surviving brother Siemowit III, and four years later (1345), both brothers inherited Rawa Mazowiecka from their uncle Siemowit II. The formal division of the paternal inheritance took place in 1349, when Casimir I received the small district of Warsaw, being the first time that this district became in the capital of a Piast Dukedom. In 1351, Casimir I increased his patrimony with the district of Sochaczew, which he received after the death of his cousin Bolesław III. On 18 September 1351, Casimir I and Siemowit II decided to paid homage to the Polish King

Casimir III the Great Casimir III the Great (; 30 April 1310 – 5 November 1370) reigned as the King of Poland from 1333 to 1370. He also later became King of Ruthenia in 1340, retaining the title throughout the Galicia–Volhynia Wars. He was the last Polish king fr ...

. In return of their submission, the Masovian Dukes received the promise that if the King died without sons, the entire inheritance of Bolesław III passed to them. In fact, they received the main district of Bolesław III,

Płock Płock (pronounced ), officially the Ducal Capital City of Płock, is a city in central Poland, on the Vistula river, in the Masovian Voivodeship. According to the data provided by Central Statistical Office (Poland), GUS on 31 December 2021, the ...

immediately, but in exchange of a payment of 2,000 fines. Casimir I died between 26 November and 5 December 1355 and was buried at

Płock Cathedral Płock Cathedral (), or the Cathedral of the Blessed Virgin Mary of Masovia, is a Roman Catholic cathedral in the city of Płock, in central Poland. It is an example of 12th-century Romanesque architecture and is the oldest and most important hi ...

. Because he never married or had children, his district of Warsaw as an emptied fief was reverted to King Casimir III; however, he agreed to transfer the entire estate to Siemowit III in exchange of a monetary compensation.

References

{{DEFAULTSORT:Casimir 01 of Warsaw 1320s births 1355 deaths Dukes of Masovia