Causes of World War I corrective." British Diplomat Arthur Nicolson wrote in May 1914, “Since I have been at the Foreign Office I have not seen such calm waters.” On 28 June 1914, Archduke Franz Ferdinand of Austria, heir presumptive to the Austro-Hungarian throne, and his wife, Sophie, Duchess of Hohenberg, were shot dead, by two gun shots in Sarajevo by Gavrilo Princip, one of a group of six assassins (five Serbs and one Bosniak) coordinated by Danilo Ilić, a Bosnian Serb and a member of the Black Hand secret society. The assassination is significant because it was perceived by Austria-Hungary as an existential challenge
German occupation of Luxembourg during World War I neutral state. The Luxembourg Crisis had seen Prussia thwart France's attempt to purchase the Grand Duchy from the Netherlands. Luxembourg's neutrality was accepted by Prussia's then-Chancellor, Otto von Bismarck, who boasted, "In exchange for the fortress of Luxembourg, we have been compensated by the neutrality of the country, and a guarantee that it shall be maintained in perpetuity." In June 1914, Archduke Franz Ferdinand, heir to the thrones of Austria-Hungary, was assassinated by pan-Slavic nationalists, leading to a sudden deterioration in relations between Austria-Hungary and Serbia. Austria-Hungary was supported by the German Empire, while Serbia had the backing of the