Answer:
The French Revolution and Napoleonic Wars unleashed a wave of modernist, liberal, nationalist sentiment throughout Europe.
Step-by-step explanation:
Before Napoleon and the French Revolution, many Europeans lived in states that did not reflect their ethnic boundaries. There was no German state, nor was there an Italian or Polish state. The Habsburg Empire contained Austrians, Hungarians, Poles, Czechs, Italians, Croats, Slovenes, and others. Italians were scattered across a collection of states, some large, such as Venice, Savoy, the Two Sicilies, and the Papal States, others smaller. There were hundreds of small German principalities, along with larger states such as Prussia, Hanover, Saxony, Baden, Hesse, Bavaria and Wurttemberg.
Napoleon re-organized borders around, in part along ethnic lines. By doing so, he acknowledged the rights of people to, if not rule themselves, be considered a Nation as such.
Despite being ultimately defeated, his actions in Europe ultimately (among other things of course) led to the contemporary Europe we know today.