In reply to the assassination, Austria-Hungary declared an ultimatum to Serbia, which was partly denied. Austria-Hungary suspended diplomatic relations and declared war. Following the Secret Treaty of 1892Russia and France mobilized their armies. Russia's mobilization set off full Austro-Hungarian and German mobilization. Quickly all the Great Powers besides Italy had taken sides and gone to war.
Many historians regard the printing press as the most important invention of the past millennium because it provided people a way to express their ideas quickly and be able to reach more people.
