How did the death of Franz Ferdinand lead to an outbreak of war all over Europe?
Because Franz Ferdinand was shot by a Serb, Austria-Hungary declared war on Serbia. Germany, being an ally of Austria-Hungary, declared war on Serbia. Russia, an ally of Serbia, declared war on Austria-Hungary and Germany. France, a ally of Russia, declared war on Germany and Austria-Hungary. Germany invaded Belgium. Great Britain, being an ally of Belgium, declared war on Germany.