1. International: struggle for hegemony and Empire outstrips the fiscal resources of the state 2. Political conflict: conflict between the Monarchy and the nobility over the “reform” of the tax system led to paralysis and bankruptcy. 3. The Enlightenment: impulse for reform intensifies political conflicts; reinforces traditional aristocratic constitutionalism, one variant of which was laid out in Montequieu’s Spirit of the Laws; introduces new notions of good government, the most radical being popular sovereignty, as in Rousseau’s Social Contract [1762]; the attack on the regime and privileged class by the Literary Underground of “Grub Street;” the broadening influence of public opinion. 4. Social antagonisms between two rising groups: the aristocracy and the bourgeoisie 5. Ineffective ruler: Louis XVI 6. Economic hardship, especially the agrarian crisis of 1788-89 generates popular discontent and disorders caused by food shortages.
Not sure which are the three main but those are some.
"<span>the assassination of Archduke Franz Ferdinand" is thought to be the spark that lit the powder-keg </span>of war at the beginning of the 20th century. A dense web of alliances was set off from this shooting.