In 1808 the kingdom passed Germany's first laws granting Jews equal rights, thereby providing a model for reform in the other German states.

Hesse's capital Cassel (modern spelling Kassel) then fulfilled the same function for Westphalia, and the king kept the court at the palace of Wilhelmshöhe, renamed Napoleonshöhe.

On its creation, the Kingdom of Westphalia comprised the following territories:[2] The new state was divided into departments, districts, and communes, similarly to France.

[4] The desire to break from the past, and not just from the random territorial divisions of the former manorial justices, especially influenced the cantonal distribution.

The former Brunswick-Wolfenbüttel merchant and man of letters, Israel Jacobson, became its consistorial president, assisted by a board of officers.

King Jérôme, reprimended by Napoleon for his poor performance at the Battle of Smolensk, abandoned his command and returned to Wesphalia.

By the end of the campaign, his troops had been practically decimated: out of the initial 25,000 soldiers and 800 officers of the Kingdom of Westphalia, only 600 and 18 returned, with 600 others defecting to Russia.

[7] In September 1813, Russian general Alexander Chernyshyov led a raid on Cassel with 1,200 to 2,300 regular cavalrymen and Cossacks, along with four to six artillery pieces.

The first quarter shows the silver horse of Westphalia; the second the lion of Hesse over the counties of Dietz, Nidda, Ziegenhain and Katzenelnbogen; the third was newly designed for non-specified territories around Magdeburg; and the fourth combined Brunswick, Diepholz, Lüneburg and Lauterburg.