The Austrian conquest of Serbia was a military action of Austria-Hungary, allowed by the treaty of Munich. it was a swift military action, with Serbia being taken in 13 days, with only 221 casualties total. The war was considered a massive success by the Austrians, with Serbia becoming a vassal of Austria-Hungary
Obviously, the main cause of this war was born out of a need for revenge for the death of Archduke Franz Ferdinand. Because of this, what would have been a massive war almost started, but fortunately for everyone, the Treaty of Munich was signed, allowing Austria-Hungary to attack the Serbs with out a huge war. dispute the fact that according to the treaty, the Austrians could not expand if they signed, they attacked Serbia, with around 20,000 men.
Very little actual fighting took place during this war. Due to the fact that Serbian resistance was minimal, the Austrians pretty much marched across the nation, with nothing more than scattered firefights. In fact, it is estimated at least 40 percent of Austro-Hungarian soldiers never fired their weapon in combat. The one notable battle of the war was the battle of Belgrade, which caused 72 of the 97 Austrian casualties. the battle was a mistake, as an order was misread to under stand "send 5,000 troops to Belgrade, while the rest attack the central portion of the country," rather than the other way around. the attack was still a success, but still caused around 80% of the war's casualties.
With the Austrian-Hungarians taking Serbia so quickly, the Serbs were in no position to negotiate, and it was well known that Austria-Hungary intended to make it a vassal state. On August 30th, they were proven right when Archduke Ferdinand Karl was appointed as ruler of the newly formed Kingdom of Serbia. Despite this, the Serbs were able to keep a large degree of their independence, although they were responsible for help protect Austria-Hungary in times of war.