(A) June 1, 1919
(B) ** June 28, 1914
(C) June 14, 1928
(D) January 1, 2017
EXPLANATIONS BELOW
Concept note-1: -Austria-Hungary declares war on Serbia, beginning World War I.
Concept note-2: -At around 11 a.m. today, two shots rang out from a street corner in the center of this city, mortally wounding the archduke Franz Ferdinand, heir to the throne of the Austro-Hungarian Empire and Sophie the Duchess of Hohenberg, his wife.
Concept note-3: -Archduke Franz Ferdinand of Austria, heir to the Austro-Hungarian throne and his wife Sophie, Duchess of Hohenberg were assassinated in Sarajevo on 28 June 1914. They were shot to death by Gavrilo Princip, a Bosnian student and member of the Serbian secret society “Black Hand".
Concept note-4: -On July 28, 1914, one month to the day after Archduke Franz Ferdinand of Austria and his wife were killed by a Serbian nationalist in Sarajevo, Austria-Hungary declares war on Serbia, effectively beginning the First World War.
Concept note-5: -World War I began after the assassination of Austrian archduke Franz Ferdinand by South Slav nationalist Gavrilo Princip on June 28, 1914. Read more about why the Balkans became the “powder keg of Europe.”