On 25 July 1914, the Austro-Hungarian Ambassador to Serbia, Baron Wladimir Giesl (pictured), sent a telegram to the Austro-Hungarian Minister of Foreign Affairs, Leopold Count Berchtold. In his short telegram, Giesl informs Berchtold that he has broken off diplomatic relations with Serbia. This is one of the key documents of the 1914 July Crisis.
Baron von Giesl to Count Berchtold. Semlin, 25 July 1914.
In consequence of an inadequate answer on the part of the Royal Servian Government to our demands of 23 July [i.e. the Austro-Hungarian ultimatum to Serbia], I have declared diplomatic relations to be broken off, and have left Belgrade with the personnel of the legation.
Source: 1919 Austro-Hungarian Red Book, with minor edits.