How did nationalism spread across europe with napoleon?

These are just the point headings, you can further explain it yourself.

Further explanation:
Within the wide swathe of territory that came under his control,
Napoleon set about introducing many of the reforms that he had
already introduced in France. Through a return to monarchy
Napoleon had, no doubt, destroyed democracy in France, but in
the administrative field he had incorporated revolutionary principles
in order to make the whole system more rational and efficient. The
Civil Code of 1804 – usually known as the Napoleonic Code –
did away with all privileges based on birth, established equality
before the law and secured the right to property. This Code was
exported to the regions under French control. In the Dutch Republic,
in Switzerland, in Italy and Germany, Napoleon simplified
administrative divisions, abolished the feudal system and freed
peasants from serfdom and manorial dues. In the towns too, guild
restrictions were removed. Transport and communication systems
were improved. Peasants, artisans, workers and new businessmen enjoyed a new-found freedom. Businessmen and small-scale
producers of goods, in particular, began to realise that uniform
laws, standardised weights and measures, and a common national
currency would facilitate the movement and exchange of goods
and capital from one region to another.
However, in the areas conquered, the reactions of the local
populations to French rule were mixed. Initially, in many places such
as Holland and Switzerland, as well as in certain cities like Brussels,
Mainz, Milan and Warsaw, the French armies were welcomed as
harbingers of liberty. But the initial enthusiasm soon turned to hostility,
as it became clear that the new administrative arrangements did not
go hand in hand with political freedom. Increased taxation,
censorship, forced conscription into the French armies required to
conquer the rest of Europe, all seemed to outweigh the advantages
of the administrative changes.