The Napoleonic wars happen, then there's the Vienna conference, and the European Concert, and nationalism is on the rise, European powers grow more imperialistic etc. Do all those things - which were mostly influenced by the French Revolution, the Enlightment and the Napoleonic Wars, and the multi-polar balance-of-power system that existed in the international stage that we call the "Concert of Europe" - must lead to a global war (nevermind who the combatants are), or at least a pan-European war? I mean, there's no way for nationalism not to rise after the Napoleonic wars, and things directly relating to nationalism have lead to the breakout of the first world war, and the congress system did not allow one nation to impose its will upon the rest of Europe, so you have no Pax [Insert Nation Here]na, and thus clashes of interests are likely to be solved through war as no greater power is going to intervene to keep the peace because there are no greater powers.