In Europe itself, you have quite major conflicts in the Franco-Prussian War, Austro-Prussian War, and the Crimean War, plus more minor conflicts around the unification (more like conquest) of Italy, the independence of various Balkan states from the Ottoman Empire starting with Greece, Prussia's war against Denmark. And then you have all of the internal civil wars or strife people usually don't call outright wars, but in the 19th century, were often quite violent. The Revolutions of 1848, for example. Or France switching governments four times (July Monarchy, Second Republic, Second Empire, Third Republic) after the restored monarchy, all of them quite violent transitions.
Not to mention the fact that the stresses of urbanization and concomitant social changes provoked a lot of resistance from the lower classes, which was often quite violent. It's not until well into the 20th century that major strikes don't involve lots of bloodshed!
19th century Europe is only peaceful relative to the quite bloody conflicts that bookended the time period, which themselves rank among the bloodiest conflicts in all of human history.