It was July 23, 1914 and a month earlier Archduke Franz Ferdinand of Austria-Hungary had been gunned down by young Serbian Gavrilo Princip -- thanks to some fairly bad luck after the initial assassination attempt that day failed.
So on the 23rd, a Thursday, the Austro-Hundarian government, at the end of its "patient tolerance," sent a strongly worded cable that demanded that the Serbian government, among other things, punish anyone believed to be involved in Ferdinand's assassination, dismantle any and all "propaganda" against Austria-Hungary, and dissolve any "subversive" anti-Austro-Hungarian groups.
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The Serbian government was also called to post publicly a statement dictated to it by Austria-Hungary denouncing any of the "propaganda." The communique demanded a response from the Serbian government by Saturday 6 p.m.
The WWI network of alliances. (Via West Point)
But before the Serbian government received the message, the wheels of war had been turning. By that point various alliances that crisscrossed the continent all but guaranteed that the assassination of the one public official would spark a conflict unlike ever before.
"A 'world war' unless Servia [sic] complies with the demands Austria has made upon it was being predicted today by diplomats and military men here," reads a report from Berlin for the Daily Capital Journal on the morning after the ultimatum.
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The New York Times wrote, "Grave importance is attached to the fact that Baron Hoetzendorf, Chief of the Austrian General Staff, yesterday visited Temesvar, from where the Austrian army would invade Servia. Seven corps have been ordered to be held in readiness and several monitors have proceeded to Semlin. In case of Servia's non-compliance with the ultimatum the army will invade the kingdom without further parley."
By Sunday morning, the world had its answer as the Times blared on its front page "Austria Breaks With Servia; King Peter [of Serbia] Moves His Capital; Russia Is Mobilizing Her Army; Berlin and Paris Mobs for War." The article describes how the Serbian government agreed to "all the demands of Austria-Hungary which will serve to suppress all criminal acts, manifestations, and disorders in neighboring countries" and encouraged "friendly" relations, but went no further. The response was apparently not enough for the Austro-Hungarian government.
"Diplomatic relations between Austria-Hungary and Servia were broken off at 6 o'clock last evening, and war is considered certain," the Times said.
The resulting four-year conflict, that introduced the world to the horrors of trench and chemical warfare, claimed the lives of an estimated 17 million soldiers and civilians.
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