Final answer:
The concept addressed is Slavic nationalism, which contributed to the assassination of Archduke Franz Ferdinand, an event that initiated World War I through the activation of a complex alliance system.
Step-by-step explanation:
The passage you've provided refers to the events leading up to World War I, and centers around the concept of Slavic nationalism and its impacts in the Balkans. Gavrilo Princip, a Bosnian Serb, assassinated Archduke Franz Ferdinand of Austria because he believed in the unification of all South Slavs in a state independent from Austria. This event set off a chain reaction within the complex web of European alliances. Serbia, with nationalist ambitions, was allied with Russia, while Austria-Hungary had alliances with Germany. The assassination compelled Austria-Hungary to demand restitution from Serbia, which led to the declaration of war that involved all these interconnected nations through a series of alliances and triggered the start of World War I.