Napoleon in Poland

The fourth coalition was assembled in and Napoleon defeated Prussia at the Battle of Jena-Auerstedt (14 October 1806).
He marched on against advancing Russian armies through Poland, and was involved at the bloody stalemate of the Battle of Eylau on 6 February 1807.
After a decisive victory at Friedland, he signed a treaty at Tilsit in East Prussia with Tsar Alexander I of Russia, dividing Europe between the two powers.
He placed puppet rulers on the thrones of German states, including his brother Jerome as king of the new state of Westphalia.
In the French-controlled part of Poland, he established the Duchy of Warsaw, with King Frederick Augustus I of Saxony as ruler. Between 1809 and 1813, Napoleon also served as Regent of the Grand Duchy of Berg for his brother Louis Bonaparte.