On July 25, Tsar Nicholas II convened a meeting of the Privy Council in Tsars' Village, at which Nicholas II approved in principle the partial military mobilization of the previous day. and the decision to mobilize only four military districts and two naval fleets. However, in essence, this military mobilization eventually covered the entire European part of Russia, including 6 military districts (not 4); Warsaw, Vilnius (Baltic region), Kazan, Moscow, Kiev, Kazan, Osad.

The period of Russian pre-war preparation was divided into several stages. In the first stage, reservists need to be recalled, naval ships return to port to prepare for battle, troops suspend vacations, and cavalry have to nail horses. Arrest suspected spies and transfer valuable items from border areas. The most important task is to deploy troops and weapons to border posts and to provide operational orders to front-line troops. This measure only requires the Secretary of War to sign an order.

In the second phase, the scope of recalled reservists will be expanded. Russian ports will then need to deploy mines, buy more horses and vehicles to transport supplies, and move the families of officers from the border to safety. The recruitment of narrow-gauge rolling stock (i.e., the European standard gauge, which Russia uses in 5-foot broad gauge) and the need for press control in Russia only required the signature of the Minister of War.

At the time of Russia's secret military mobilization, the French government, as an ally, was of course clear. To this end, the French ambassador to Russia, Pareologue, sent a telegram to the Acting Minister of Foreign Affairs, Pihenfanneu Martin, about the secret Russian mobilization in response to the Austro-Hungarian attack on Serbia. It was also informed that the military attache of the embassy, Dragish, had been stationed in the Red Village and was a liaison officer between the Minister of War Sukhhomlinov and the Grand Duke Nicholas.

Also on this day, Dragish received a secret instruction from the French General Staff to communicate with Russia on the basis of the inevitability of war in Europe. So the head of the French government is still sailing on the sea, and the diplomatic and military liaison officers in Russia have entered a state of war, and they maintain contacts with Paris in the course of Russia's secret military mobilization.

At 3 p.m. on the 25th, the Serbian government ordered a military mobilization against Austria-Hungary, and Serbia began to ship central bank reserves and documents of the Ministry of Foreign Affairs to the interior. The garrison of the capital has already entered field fortifications, and warehouses of munitions near Belgrade have been transferred. All this was seen by the Austro-Hungarian ambassador Gisle, who knew that Serbia would not agree to the ultimatum, and Austria-Hungary did not think that they would agree.

At 5:55 p.m., Serbian Prime Minister Pašić arrived at the Austro-Hungarian embassy, and Pašić handed the diplomatic note to Gisr and spoke it in staccato German. "We can only accept some of your requests...... For those remaining demands, we can only hope for the noble and noble qualities that you should have as an Austrian general. (This is the original words of history)

Gisr unceremoniously took a look at the reply and immediately made a judgment that Serbia's reply was not sincere, and Serbia did not even publicly apologize in this diplomatic note. He returned the documents to Pašić, and then he informed Serbia that he had not received a response that met the requirements. He will leave Belgrade in the evening with the entire Austro-Hungarian embassy.

Gisr didn't scare anyone, and his men burned the diplomatic codebook in a matter of minutes. Gisr evacuated the embassy at 6:15 p.m. with his wife and the entire diplomatic corps, and on his way to the train station he saw the streets full of soldiers, although the Serbian army did not detain him. At 6:30 a.m. he left Belgrade by train, and at 6:45 a.m. Gisr and his party entered Austro-Hungarian territory. American historian Sidney Fay said this set a record for the speed of severing diplomatic relations.

The Austro-Hungarian government received information from Gisle at 7:45 a.m., and that the military mobilization for the war had also taken place after Foreign Secretary Bertold and War Secretary Krobatin had arrived at the palace to meet Franz Joseph. The old emperor agreed to mobilize for war, and at 9:23 the military mobilization order was issued by the Minister of War, Krobatin.

And in fact, with the efficiency of the Austro-Hungarian government, according to the words of the Chief of the General Staff Conrad. "It won't start until the 28th."

Foreign Secretary Bertold had previously consulted with him about the military mobilization plan, but because of the summer holiday (in July, the Austro-Hungarian army released people to collect food), the head of the Austro-Hungarian army could not let the army end the vacation early (which can be seen in the chaotic management of the Austro-Hungarian army).

Moreover, the military mobilization order of Austria-Hungary was also aimed at two practical situations, "B" plan was to deal with the Balkan operation, and "R" plan was to deal with the Russian war. The two plans are practically mutually exclusive, since the battlefield is in opposite directions. It stands to reason that Plan "B" should be used to fight against Serbia, but if Russia mobilizes militarily first, it will have to switch to Plan "R", which will also cause confusion in the Austro-Hungarian army, and at the same time, it will also lead to a shortage of troops for Austria-Hungary to attack Serbia.

In Conrad's plan, it would take the second week, August 12, for Austria-Hungary to be ready to invade Serbia. Now Foreign Minister Bertord could not wait, he believed that by that time the Salvian question could not be localized, and Russia would definitely intervene. In fact, Russia had already begun a secret military mobilization, and his idea was frustrated.

Germany, which was the greatest support behind Austria-Hungary, did not return to Berlin until July 27, when the Kaiser, Chief of the General Staff, General Moltke Jr., and Admiral Tirpitz, returned to Berlin. Chancellor Holwig, who had returned two days earlier, told them about the current austro-Hungarian situation. Faced with the violent Russian reaction caused by the current Serbian question, Wilhelm II ordered the return of naval ships to the port of Kiel in response to the partial mobilization of Russia.

In fact, German intelligence officers had already detected the Russian military mobilization, and in Kiev an artillery division was seen heading west, and intelligence officers in Riga reported that the local army had begun to lay mines outside the port. The most important thing was that the German consul in Warsaw sent a telegram back; All the troops were recalled from the training grounds, a large number of infantry and cavalry were transported from Brest to Lublinko and Verek (towns near Warsaw), and hundreds of military columns were transported back and forth on the Brest and Tautusk roads throughout the night. All this led the German government to believe that Russia was not only a military mobilization against Austria-Hungary, but also against Germany.

At 11:10 a.m. on July 28, Austria-Hungary declared war on Serbia. The diplomatic note declaring war stated that the Serbian Government had not complied with the request of the Austro-Hungarian side in the note of 23 July 1914 and that Austria-Hungary could only protect its rights and interests by its own strength, and that it was compelled to resort to force to this end.

This was also a fait accompli that Austria-Hungary Foreign Minister Bertold hoped to illuminate, except that he did not know that a major war in Europe that lasted for four years had been ignited by him.