The events leading up to and including WWI involved much of Europe, including Germany, Austria-Hungary, Russia, the Balkans (the southern Slavic countries), France, and Britain.
During these events, three people played important roles. Otto Von Bismarck toiled daily for the safety of Germany, creating many strategic alliances. Kaiser Wilhelm was Germany’s king, who ended up removing Bismarck and ruling during the war. Because of his conciliatory policies, Archduke Franz Ferdinand became the ideal candidate for assassination, kick-starting the war.
Bismarck was removed from office because the Kaiser believed that there was no possible way that the most absolutist power (Russia) would ally with the land of revolution itself (France). (The two did actually ally.) Then, a Serbian nationalist terrorist cold-bloodedly murdered the Archduke and heir to the throne of Austria on June 28 1914. Because he had been acting in favor of Serbia, the assassin was sheltered by his home country while Germany pushed Austria for action. Upon Austria’s July 28 1914 declaration of war on Serbia, Russia mobilized to aid its Slavish ally. Discovering a way to enter the conflict, Germany invaded Belgium on July 28 1914 while declaring war on Russia.
The nationalist Serbs were hotly determined to unify the Slavic nations under Serbia since the fall of the Ottoman Empire. For this to happen, the Slavs would need to be agitated in their current countries (such as Austria-Hungary) and secede to join Serbia. Unknowingly, Archduke Franz Ferdinand stoked the fire of the Serbian terrorists. His policies were focused on contenting rather than upsetting the Austrian Slavs within Austria-Hungary, painting a bull’s-eye on his back. Essentially, WWI began because the upstart country Serbia craved unification among the Slavs, which blew up in their faces.