The Road to 1914

On June 28, 1914, a Bosnian Serb nationalist named Gavrilo Princip shot Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, in Sarajevo. Austria-Hungary blamed Serbia and, backed by a German promise of support known as the blank check, sent Serbia an ultimatum on July 23 designed to be rejected. Serbia's reply was conciliatory but not total, so Austria-Hungary declared war on July 28. Russia, Serbia's protector, began mobilizing. That single word, mobilization, is where diplomacy stopped mattering.

By 1914, every great power's mobilization plan ran on fixed railway timetables moving millions of men and tons of supplies to exact points on exact days. These plans could not be started partway or paused once begun without creating chaos, so each government's generals argued that any delay would leave their army exposed and behind a rival's schedule. Germany's Schlieffen Plan made this worse: it required attacking France first, through Belgium, before turning east against Russia, so Russian mobilization against Austria-Hungary forced Germany to mobilize against France too. Germany declared war on Russia on August 1 and on France on August 3, then invaded Belgium, which pulled in Britain on August 4.

The alliance blocs explain why a Balkan quarrel became a general war rather than a local one. The Triple Alliance bound Germany, Austria-Hungary, and Italy; the Triple Entente linked France, Russia, and Britain. Once Austria-Hungary and Serbia fought, every ally's treaty commitments and military timetables dragged in the rest, connecting this topic directly to the long buildup of rivalry, imperialism, and arms racing covered alongside it.