Subdivisions of the Duchy of Warsaw were based ondepartments that were headed byprefects. The subsidivions were based on theFrench model following the erection of theDuchy of Warsaw byNapoleon. The departments were in turn subdivided into traditional Polishpowiats (counties). Initially six departments were created from the territory annexed from theKingdom of Prussia. After the 1809Polish–Austrian War and theTreaty of Schönbrunn the duchy's territory was expanded and their number increased to ten. Each department was named after its capital city.
The departments were divided into powiats, and the powiats were divided into urban and ruralgminas. Each department was governed by a prefect, while counties were administered by a prefect deputy (Polish: podprefekt). Main cities of the Duchy (Warsaw, Poznan, Kalisz, Torun, Lublin, Kraków and Sandomierz) were administered by mayors (Polish: prezydent), who were nominated by KingFrederick Augustus I. The initial six departments were created by a Napoleon’s decree of January 14, 1807.
In January 1807 the Duchy of Warsaw was divided into the following departments:
Added in 1809, after the Polish - Austrian War (the four departments of former West Galicia were created by a royal decree on February 24, 1810. On April 17, 1810, they were divided into forty counties):
In 1815 the Duchy of Warsaw was divided into Prussian-administeredGrand Duchy of Posen and Russian-controlledCongress Poland. In 1816, the departments of Congress Poland were turned intovoivodeships (seeAdministrative division of Congress Poland).