Sure, but still quite a lot of conflict compared to now (my point about "relative"). Levels that I think people greatly underestimate. And those first 15 years were VERY bloody. (Napoleonic Wars was 1803-1815 for those that don't know and killed between 3.5m and 7m people)
But bloody European wars still include the Caucasian War, the First Carlist War (where 5% of the Spanish population died), Austro-Prussian, Franco-Prussian, the Third Carlist War, and Russo-Ottoman wars. Not to mention some very bloody revolutions: Greek, Hungarian, Italian, French (which cascaded), and so on.
I think it's also important to remember that Europe in 1800 had about 195 million people and rose to a bit over 400 million by the end of the century. Which should significantly influence how one thinks about the causality levels when considering today's >740 million.
Not to mention all the conflicts outside of Europe (many including European powers). The Dungan "Revolt" and Miao Rebellion were some of the bloodiest conflicts in human history. It was an especially bloody century for China.
I'm not sure I'd say that Congress of Vienna achieved lasting peace and I think we both know that either side of that argument can be argued. Especially on the distinction of how you consider peace (people killing one another or conflicts between nations?) and locality (conflicts between European powers on European soil or conflicts involving European powers outside Europe?). Either way, the body count is very high.
Independently, the Napoleonic Wars, (and outside Europe) Red Turban Rebellion, Mfecane, Miao Rebellion, Dungan Revolt, and Taping Rebellion have higher death tolls than all of the global conflicts since 2000[0]. These numbers aren't even normalized to population change[1]. So while maybe not as bloody (in Europe) as the 18th century, I'd still claim it was extremely bloody in the relative sense (which was my point)
[1] Recognizing that world populations were 1bn in 1800, 1.2bn in 1850, 1.6bn in 1900, 6.1bn in 2000, and 8bn today. This represents a monumential shift and should significantly affect how one interprets casualty numbers.
