Napoleonic Wars (1803-1815)

Napoleon's campaigns across Europe killed an estimated 5 million people but also spread revolutionary ideals — liberty, equality, the Napoleonic Code of law, meritocratic government — across a continent dominated by hereditary aristocracy. The Congress of Vienna (1815) created a new European order that prevented great-power war for nearly a century, while the nationalism Napoleon unleashed would produce both German and Italian unification.