After the outbreak of the Austro-Serbian War, the Austro-Hungarian Army garrison in Bosnia and Herzegovina marched into Belgrade. The war went smoothly at first, and the Austro-Hungarian army did not face any resistance as Serbia took refuge for the time being.

The rapid advance of the Austro-Hungarian army rejoiced under the deliberate propaganda of Vienna, and for a time the contradictions in the country seemed to disappear, and even the sluggish economy showed signs of recovery.

And at this time, the Hungarians were patiently waiting for their chance, and any bad news from the front would be a signal for them to launch.

And the Serbs did not disappoint them.

At this time, Serbia was not the Serbia that had reaped the benefits of the two Balkan wars and became stronger. Peter I did not insist on pursuing the strategy of "keeping the enemy out of the country" as he did in World War I, and shouted the brain-dead declaration of "not a single step back" with full self-confidence.

Therefore, the Serbs decided that it was better to defend the border than to defend the danger, and deployed their troops in the capital Belgrade, and in the western mountains on the east bank of the Drina River.

The Serbian army under General Radomir Putnik did not attack when the Austro-Hungarian army had crossed the Drina River, knowing that if the Austro-Hungarians used river gunboats, their own army would be bombarded by naval artillery.

The Austro-Hungarian army, which crossed the Drina River and was ready to stab like a dagger into the Serbian hinterland, met with resolute resistance from Radomir's men at the Zer and Evelk Mountains.

Because the Serbian army relied on the terrain to build a defensive position, on the one hand, the terrain of the western mountains made it difficult to transport heavy weapons, and on the other hand, because of the lack of preparation for the hasty start of the battle, the Austro-Hungarian army, which lacked heavy artillery, had to use infantry to attack the fortification, and after only four days of fighting, the Austro-Hungarian army suffered nearly 20,000 casualties, and only advanced 15 kilometers.

The front was at a stalemate, and the Austro-Hungarians, realizing that a quick victory was no longer possible, had to stop their offensive, and the Austro-Hungarian commander-in-chief, Grand Duke Albrecht Friedrich Rudolf, had to mobilize 10 divisions and a large amount of heavy equipment from Austria-Hungary in an attempt to crush the Serbs with superior forces.

However, Archduke Albrecht Yan Zòng overestimated the Austro-Hungarian railway transport capacity, and the surging military trains and poor railway dispatch command almost paralyzed the Austro-Hungarian railway system.

It was not until August that the 10 divisions were fully equipped with troops and equipment, and the Austro-Hungarian army's hopes of taking Belgrade to celebrate the Emperor's birthday (18 August) were completely dashed.

In mid-August, 170,000 Austro-Hungarian troops marched from Vojvodina into Serbia, and under the cover of the river flotilla, the Austro-Hungarian army crossed the Sava River and directly threatened Belgrade, the capital of Serbia.

In order to defend the capital, the Serbian troops defending Belgrade had to take the initiative and were ready to attack the Austro-Hungarian army while it was not gaining a firm foothold. However, the Serbs, who had gone very smoothly in the previous battle, made a mistake this time, and the Austro-Hungarian machine guns let the Serbs know what the brainless attack would be.

This time, the Austro-Hungarians directly transported all the 50 machine guns they had just bought, and no matter how heavy the Maxim was, it was lighter than the artillery, and the Austro-Hungarians, who attached the Maxim to the artillery unit, brought this big killer weapon this time. This wise move gave the Austro-Hungarians a big advantage this time, and in the battle between the two armies, Maxim once again showed his slaughter efficiency.

During the half-day engagement, the Serbs left nearly 6,000 bodies in front of the Austro-Hungarian makeshift positions. The Serbs, having suffered heavy losses, had to withdraw to Belgrade and hold on, while the Austro-Hungarian army was directed under Belgrade, and Vienna was optimistic that the capture of Belgrade was just around the corner and victory was within reach.

However, the victory of the Austro-Hungarians ended there.

In September, when Austria-Hungary was fighting bloody battles with the Serbian defenders in Belgrade, the Serbs threw in their last reserves. And the Serbs were very bold, even crazy, to throw their reserves into the western mountains instead of going to Belgrade to relieve the siege.

The aim of the Serbs was to achieve a decisive victory over Austria-Hungary in the western mountains, so that they could withdraw from it and then return to Belgrade.

The idea is good, but in practice, the judgment of the situation is too optimistic.

At this time, more than 60,000 Austro-Hungarian troops trapped in the mountains and already greatly damaged in the face of the Serbian army's crazy counterattack, and after paying more than 20,000 casualties again, they were forced to retreat back to the banks of the Drina River after completely losing their offensive capabilities.

The first step of the Serbs, the goal of achieving a decisive victory was achieved. But the Serbian troops, who also suffered heavy losses in the frantic counterattack, were unable to relieve the siege of Belgrade.

But a big defeat is enough for some people with ulterior motives. This retreat of the Austro-Hungarian army detonated the powder keg in the country. At this time, the Austro-Hungarian army besieging Belgrade under the command of Archduke Albrecht suffered heavy casualties, but the Serbian defenders were also not doing well. Seeing that the fall of Belgrade was imminent, something happened in the Austro-Hungarian country.

Troops who lost more than 40,000 men in the western mountains not only did not make any progress, but were beaten back. Together with the loss of more than 10,000 troops under Belgraden, Austria-Hungary lost a total of more than 50,000 men.

The citizens of Vienna didn't care how many Serbs died, they didn't care that Belgrade was about to fall, they lost 50,000 people without making any progress, and they were "disgraced" beaten back by the Serbs. Unable to stand it, the Austro-Hungarian people began to take to the streets to denounce the incompetence of the army, and then began to point the finger at the government.

In such a fuss, Austria-Hungary no longer had the energy to continue the war, and the finances, which had been encouraged to support, could no longer hold on. Unable to receive logistical support anymore, the Grand Duke of Albrecht was forced to stop the offensive on Belgrade and withdraw to the vicinity of the Sava River.

This retreat marked the inability of the Austro-Hungarian army to launch a large-scale military operation against Serbia, and also marked the complete military defeat of Austria-Hungary.

This retreat intensified the wave of protests in Austria-Hungary. The military defeat of Austria-Hungary caused unrest at home, and the emergence of a run on the bank began to drain every penny of savings in the Austro-Hungarian bank, and the exchange of gold for huàn left the Austro-Hungarian treasury empty. The collapse of the economic credibility of banks and countries has turned newly issued krona into waste paper in an instant.

The collapse of the economic system led to an angry populace besieging the government, and radicals began to take aim at the emperor himself.

At this time, the Hungarians took action, and Shopari Gyulo declared that Hungary should not pay for Vienna's defeat, and that Vienna's economic losses should not be borne by the Hungarians, and that Budapest would no longer accept Vienna's leadership until the first question was resolved. Although it seems that there is still room for turnaround, everyone knows that Austria-Hungary is finished.

Hungary's statement prompted other ethnically majority provinces to make similar demands, and Vienna was in a state of flux.

At this time, an envoy from Germany arrived at Schönbrunn Palace and brought a German solution to Joseph: His Majesty Joseph abdicated and recognized the independence of Hungary. Let the German Crown Princess Marie Valerie be Queen of Austria, then Germany will put pressure on Hungary (in fact, everyone has already agreed) to make Marie Queen of Hungary, and the Habsburgs will continue to retain the St. Stefan crown. In this way, Germany, as the husband of the Austrian queen, had enough excuses to help the Habsburgs through this crisis.

The Austro-Hungarian Empire was divided into three, and the southern regions of Croatia, Slovenia, and Vojvodina merged into a new kingdom, with Austro-Hungarian Crown Prince Ferdinand as king.

The Germans played their calculations very well, Croatia and Slovenia had a high degree of identification with Austria-Hungary, 3% of the Slovenes were killed or injured in the First World War for Austria-Hungary, and the same was true for the Croats, Vojvodina was taken over by the Habsburgs in the early 18th century, although it was under the jurisdiction of Hungary after the establishment of the Austro-Hungarian Empire, but the Hungarians did not mind handing it over as compensation to the Habsburgs.

Ferdinand was also a fairly enlightened monarch, and it shouldn't be a problem to gather these people. Coupled with Germany's backing, at least it would not be a problem to contain Serbia's continued expansion. Who knows if these-stirring sticks will really think that they are fighting themselves, the disintegration of Austria-Hungary, and their self-confidence will burst, and as a result, they will engage in three or four in the Balkans.

Faced with the conditions of the Germans, His Majesty Joseph hesitated. Mary married Jochen and thus did not renounce her inheritance. As a Habsburg princess, she did have the right to inherit the Austrian and Hungarian crowns, and it was probably the best choice for her to become the queen of Austria and Hungary, but Joseph couldn't make up her mind.

He came to the throne in 1848 during the revolution that swept through Austria, and the defeat in the Austro-Prussian War brought the Kingdom of Austria to the near collapse, and he persuaded the Hungarians to establish the Austro-Hungarian Empire.

Now that he has led to the collapse of the empire because of the defeat to an insignificant opponent like Serbia, he has survived the more dangerous and difficult situations before, and now he has to give up on his own, and he is unwilling.

Seeing that Franz Joseph I hesitated, the Germans did not urge, and resigned very interestingly, leaving His Majesty Joseph alone in contemplation.

But what Franz Joseph I didn't know was that the Germans were actually prepared for both. While visiting Schönbrunn Palace, the Germans arrived at Albertina Palace to visit Archduke Albrecht, who had already returned home.