# Casimir defeats Masław of Masovia (1047)

URL: https://poland-history.com/timeline/1047-casimir-defeats-maslaw-of-masovia
Location: Masovia
Categories: battle

Casimir defeated the Masovian ruler Masław, restoring Masovia to the Piast state. Within the broader Piast Monarchy period: Under Mieszko I and his successors the Piast state accepted Christianity, gained its own church province and royal crown, and fought to hold its place between the Holy Roman Empire, Bohemia and Kievan Rus'. At this point in the timeline (1047), the governing authority was Casimir I the Restorer (Duke of Poland). Rebuilt the Piast state after the crisis of the 1030s, recovering Masovia and Silesia and moving the centre of power to Kraków. Casimir defeats Masław of Masovia mattered because it changed the military or territorial balance and influenced the political choices that followed. The event is placed here so readers can follow it alongside changes in government, warfare, society, religion and culture across Polish history.

## Why it matters
Casimir defeats Masław of Masovia mattered because it changed the military or territorial balance and influenced the political choices that followed.

Ruler at the time: [Casimir I the Restorer](https://poland-history.com/rulers/casimir-i-the-restorer)

## Sources
- [Wikipedia — Miecław](https://en.wikipedia.org/wiki/Miec%C5%82aw)
- [Encyclopaedia Britannica topic lookup — Casimir defeats Masław of Masovia](https://www.britannica.com/search?query=Casimir+defeats+Mas%C5%82aw+of+Masovia)
- [Wikipedia — History of Poland during the Piast dynasty (period overview)](https://en.wikipedia.org/wiki/History_of_Poland_during_the_Piast_dynasty)