Having received an unsatisfactory answer to the 23 July ultimatum, Austria-Hungary broke off diplomatic relations with Serbia.
Baron von Giesel to Count Berchtold. Semlin, 25 July 1914.
In consequence of an insufficient answer on the part of the royal Servian government to our demands of the 23rd inst. I have declared diplomatic relations to be broken off and have left Belgrade with the personnel of the legation.
Source: Austro-Hungarian Red Book