This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
On the morning of 28 June 1914, a nineteen year old Bosnian Serb named Gavrilo Princip shot and killed Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, and his wife Sophie as their car passed through Sarajevo. It was the second assassination attempt against the couple that same morning; the first, a bomb, had missed. Nobody in Europe expected this killing to become a world war. Assassinations and Balkan crises had been common for years, and every earlier one had stayed local. What made 1914 different was not the act itself but the five weeks of decisions that followed, a sequence historians call the July Crisis. Austria-Hungary blamed the Serbian government for the killing and wanted to punish Serbia decisively, but it feared Russia would intervene on Serbia's behalf. On 5 July, Germany removed that fear by promising Austria-Hungary unconditional support, the so called blank cheque, whatever Austria-Hungary chose to do. Armed with that guarantee, Austria-Hungary issued Serbia an ultimatum on 23 July with terms deliberately written to be unacceptable, including a demand that Austro-Hungarian officials be allowed to conduct their own investigation inside Serbian territory. Serbia's reply conceded nearly everything except that one clause, an extraordinary act of restraint that Austria-Hungary rejected anyway. On 28 July, exactly a month after the assassination, Austria-Hungary declared war on Serbia. Russia, seeing itself as Serbia's protector, ordered general mobilization on 30 July. Because Germany's own war plan depended on defeating France quickly before Russia's larger army could fully mobilize, Russian mobilization looked to German generals like the war clock had already started. Germany demanded Russia stand down; when the deadline passed unanswered, Germany declared war on Russia on 1 August and on France on 3 August. The final step brought Britain in. Germany's war plan required marching through Belgium to reach France, violating an 1839 treaty guaranteeing Belgian neutrality that Britain itself had signed. Germany invaded Belgium on 4 August; within hours Britain declared war on Germany, and with the British Empire's entry a Balkan quarrel between two second and third rank powers had become a war among every major power in Europe, all within five weeks of a single shooting in a provincial city few outside the region had heard of. What turned a local killing into a global catastrophe was not any single villain but a system: rigid alliance commitments, war plans built around inflexible mobilization timetables, and leaders who each judged that backing down would cost more than fighting.