How did Napoleon create the Duchy of Warsaw in 1807?

The Duchy of Warsaw was established by Napoleon in 1807 following his military victories over Prussia and a subsequent compromise peace with Tsar Alexander I at Tilsit.12

The creation of the state was driven by several key factors:

• Military Collaboration: After French troops entered Prussian-occupied Poland in 1806, General Jan Henryk Dąbrowski called on Poles to organize armed units. Polish troops played a significant role in the ensuing campaigns, compelling Napoleon to acknowledge their contributions.2
• Diplomatic Settlement: The duchy was formally created through the Treaties of Tilsit (July 1807). It was composed primarily of central Polish provinces that had been absorbed by Prussia during the Second and Third Partitions of Poland.12
• Governance: To avoid offending the partitioning powers, the territory was named the Duchy of Warsaw rather than Poland. Napoleon dictated its constitution, which was based on the French model, and appointed Frederick Augustus I, the king of Saxony, as its ruler.12

The duchy served as a French outpost in the east and a symbol of hope for the restoration of the Polish nation.12