Cologne lost its status as a free
city during the French period. According to the Peace Treaty of
Lunéville (1801) all the territories of the Holy Roman Empire on
the left bank of the Rhine were officially incorporated into the
French Republic (which already had occupied Cologne in 1798).
Thus, this region later became part of Napoleon's Empire.
Cologne was part of the French Département Roer (named after the
River Roer, German: Rur) with Aachen (Aix-la-Chapelle) as its
capital. The French modernised public life by introducing the
Code Napoleon as civil code and removing the old elites from
power, to cite two examples. The Code Napoleon was in use in the
German territories on the left bank of the Rhine until the year
1900, when for the first time the German Empire passed a
nationwide unique civil code ("Bürgerliches Gesetzbuch"). In
1815, at the Congress of Vienna, Cologne was made part of the
kingdom of Prussia.
