Ultimatum to Serbia
Having received the wholehearted support from Germany, Austria sent an ultimatum to Serbia on July 23, 1914. The ultimatum was to be answered within 48 hours. It included the following demands:
(i) Serbia was to suppress all anti-Austrian (and Pan-Slav) publications, societies and propaganda.
(ii) Serbia was to dismiss all anti-Austrian officials objected by Austria.
(iii) Austrian police and officials were to enter Serbia and to take part in the Serbian police force in order to carry out the suppression of anti-Austrian activities and investigations concerning the Sarajevo murders.
Serbian reply
These demands infringed Serbian sovereignty. Austria expected that Serbia would reject, thus giving her the excuse to declare war. Instead, Serbia accepted the first two demands and suggested the third be submitted for arbitration by the Hague Tribunal. William II was satisfied with the Serbian reply and did not feel the need to punish Serbia with a war. He declared, "a brilliant diplomatic triumph, no excuse for war."
2. Outbreak of War - July 1914
War declared
Austria was still determined to destroy Serbia. After declaring the Serbian reply unsatisfactory, the Austrian government simply declared war anyway on July 28. The bombardment of Belgrade began on July 29.
Serbia mobilized before answering the ultimatum and rejected the key demand. At that time Russia issued a pre-mobilization order.
That month before the start of the war was a time of great confusion in Austrian, German, and Russian governments, -- which all lacked adequate crisis management mechanisms. It is possible to find a quote from the Keiser, for example, supporting several contradictory positions, -- depends which minister he spoke to just before that.
I will refer to the Keegan's book and give a more substantive response later.
The night and most of Saturday remained for it to be seen what the Serbs would do. On the morning of 25 July they were still reconciled to capitulation, though reluctantly and with occasional bursts of belligerence. Then, during the afternoon, word was received from their ambassador ad the Tsar's country palace tha tthe mood there was fircely pro-Serbian. The Tsar, though not yet ready to proclaim mobilisation, had announced the preliminary "Period Preparatory to War" at eleven o'clock. The news reversed everything the Serbian ministers had decided. In the morning they had agreed to accept all ten Austrian demands, with the slightest reservations. Now they were emboldened to attach conditions to six and to reject aboslutely the most important, that Austrian officials be allowed to take part in the investigation of the assassinations on Serian territory. In the hurried hours that followed, the reply to the note was drafted and redrafted, lines crossed out, phrases corrected in ink. As would happen in the Japanese embassy in Washington on the night before Pearl Harbor, the typist gave way to nerves. The finished document was an undiplomatic palimpsest of revisions and afterthoughts. With a quarter of an hour in hand, however, it was finished, sealed in an envelope and taken by the Prime Minister himself, Nicholas Pasic, for delivery to the Austrian ambassador. Within an hour of its receipt, the personnel of the legation had boarded the train for the Austrian frontier and left Belgrade.There followed a curious two-day intermission, Sunday and Monday 26-27. Serbia mobilised its little army, Russia recalled the youngest reservists to the units in its western military districts, there wqere scenes of popular enthusiasm in Vienna over the government's rejection of the Serbian reply and similar scenes in German cities, including Berlin. On Sudnay, however, the Kaiser was still at sea [on vacation], while Poincare and Viviani, the French Foreign Minister, aboard La France, did not receive a signal urging their immediate return until that night. Meanwhile there was much talk, reflective and anticipatory, rather than decisive or belligerent. Bethmann Hollweg instructed the German ambassadors in London and Paris to warn tha tthe military measures Russia was taking could be judged threatening. The German ambassador in St. Petersburg was told to say that the measures, unless discontinued, would force Germany to mobilise which "would mean war". Bethmann Hollweg learnt from him in reply that the British and French were working to restrain Russia while Sazonov, the Russian Foregin Minister, was moderating his position. The Kaiser and the Austrian government were informed. The British Foreign Office, working from information of its own, perceived a hope that the Russians were ready to acquiesce in a mediation by the United Kingdom, France, Germany and Italy. There was, briefly, the circulation of a feeling that the crisis, like those of 1909 and 1913, might be talked out. [This must be when the Kaiser praised his diplomats].
The weakness of that hope was the ignorance and misunderstanding among politicians and diplomats of how the mechanism of abstract war plans, once instigated, would operate. Only Sir George Buchanan, the British ambassador in St. Petersburg, and Jules Cambon, the French ambassador in Berlin, fully comprehended the trigger effect exerted by one mobilisation proclamation on another and the inexorability of deployment once begun.