On 23 July 1914, the Austro-Hungarian Minister of Foreign Affairs Leopold Count Berchtold (pictured) sent an urgent telegram to the Austro-Hungarian Emperor Franz Joseph’s Cabinet Director Baron von Schiessl-Perstorff. In his telegram, Berchtold confirms the delivery of the Austro-Hungarian ultimatum to Serbia at 18:00.
Count Berchtold to Baron von Schiessl-Perstorff in Ischl. Vienna, 23 July 1914.
I must beg your Excellency to inform His Imperial and Royal Apostolic Majesty in my name that the Imperial and Royal Minister in Belgrade has presented the note concerning the Servian movement to the Servian Finance Minister Pacu, who represents the Premier, at 18:00 this afternoon.
The term of 48 hours for the answer therefore expires on Saturday 25 July at 18:00.
Source: 1919 Austro-Hungarian Red Book, with minor edits.