Duchy of Greater Poland

The Duchy of Greater Poland was a district principality that encompassed much of the historical region of Greater Poland, with a territory roughly corresponding to the present-day Greater Poland Voivodeship in west-central Poland. It emerged in the 12th century following the 1138 testament of Bolesław III Wrymouth, which divided the previously unified Kingdom of Poland into several hereditary duchies, initiating a period of feudal fragmentation. Although nominally part of the Polish realm, the duchy functioned as a semi-autonomous Piast principality, governed independently by its own dukes.

In 1177, the Duchy of Greater Poland was subdivided into the principalities of Poznań, Gniezno, and Kalisz following the deposition of Mieszko III the Old, whose authoritarian rule had provoked opposition among the nobility and rival Piast princes. This internal conflict led to a redistribution of power within the region. The principalities were later reunited in 1279 under Przemysł II, forming a unified duchy that lasted until 1320, when it was reabsorbed into the restored Kingdom of Poland. The duchy's capital was Poznań, and its territory closely aligned with that of the modern Greater Poland Voivodeship.