On this day in 1914, Baron Giesl von Gieslingen, ambassador of the Austro-Hungarian Empire to Serbia, delivered an ultimatum to the Serbian foreign minister asking, inter alia
, that the Serbs let the Austro-Hungarians take over the investigation of the assassination of Archduke Franz Ferdinand and his wife in Sarajevo nearly a month before. An answer within 48 hours was demanded. The Serbs replied within the time limit and agreed to everything but allowing the Austro-Hungarians to investigate. It was not good enough and the leaders of the Great Powers of Europe were unable either to control or to placate their lesser allies and keep the diplomatic process going. Three days later, the Austro-Hungarians declared war on Serbia and the rest of Europe's monarchs and leaders followed suit, declaring war on each other's countries during the next month for reasons not fully clear despite close study for nearly a 100 years.