Napoleon replaced existing Monarchs with members of his own family. His aim was to replace existing empire with one of his, which would have made him and his family rule wholly. Resistance to to French occupation and French puppet rulers was often based on nationalist sentiments, but it's doubtful whether it would have remained a popular cause with the masses after Napoleon's final defeat.
Least common multiple (LCM) of 10 and 20 is 20.
