Civilians near the Austrian lines in Serbia being strung up as a reprisal for guerrilla resistance to the invaders, 1916.

 

The Austro-Hungarian Armed Forces occupied Serbia from late 1915 until the end of World War I. Austria-Hungary's declaration of war against Serbia on 28 July 1914 marked the beginning of the war. 

After three unsuccessful Austro-Hungarian offensives between August and December 1914, a combined Austro-Hungarian and German offensive breached the Serbian front from the north and west in October 1915, while Bulgaria attacked from the east. By January 1916, all of Serbia had been occupied by the Central Powers.

Serbia was divided into two separate occupation zones, one Bulgarian and the other Austro-Hungarian, both governed under a military administration. Germany declined to directly annex any Serbian territory and instead took control of railways, mines, and forestry and agricultural resources in both occupied zones. 

The Austro-Hungarian occupation zone covered the northern three-quarters of Serbia. It was ruled by the Military General Governorate, an administration set up by the Austro-Hungarian Army with a military governor at its head, seconded by a civil commissioner. The goal of the new administration was to denationalise the Serb population and turn the country into a territory from which to draw food and exploit economic resources.

 In addition to a military legal system that banned all political organizations, forbade public assembly, and brought schools under its control, the Austro-Hungarian Army was allowed to impose martial law, practice hostage-taking, burn villages in punitive raids and respond to uprisings with public hangings and summary executions.

 During the occupation, between 150,000 and 200,000 men, women and children were deported to purpose-built internment and concentration camps in Austria-Hungary, most notably Mauthausen in Austria, Doboj in Bosnia, and Nagymegyer, Arad and Kecskemét in Hungary.

In September 1918, Allied forces, spearheaded by the Serbian Second Army and the Yugoslav Volunteer Division, broke through the Salonica front, leading to the surrender of Bulgaria on 30 September, followed by the quick liberation of Serbia and the retreat of all remaining Austro-Hungarian troops by the end of October. By 1 November 1918, all of pre-war Serbia had been liberated, bringing the occupation to an end.

 on 28 June 1914, the heir to the Habsburg throne, Archduke Franz Ferdinand, was assassinated by Bosnian Serb student Gavrilo Princip in Sarajevo. The preservation of Austria-Hungary's prestige necessitated a punishing attack on Serbia, which the Austro-Hungarian leadership deemed responsible for the murder. The Austro-Hungarian military leadership was determined to quash Serbia's independence, which it viewed as an unacceptable threat to the future of the empire given its sizeable South Slavic population.

On 28 July 1914, exactly one month after Franz Ferdinand's assassination, Austria-Hungary declared war on Serbia. That evening, Austro-Hungarian artillery shelled the Serbian capital of Belgrade from the border town of Semlin (modern-day Zemun), effectively starting World War I. Command of the Austro-Hungarian invasion force was delegated to Feldzeugmeister Oskar Potiorek, the Governor-General of Bosnia and Herzegovina, who had been responsible for the security of Franz Ferdinand and his wife Duchess Sophie of Hohenberg in Sarajevo.[2] On the morning of 12 August 1914, the Austro-Hungarian Fifth Army crossed the Drina River, effectively starting the first invasion of Serbia.

Šabac, pictured in August 1914, was the first target of the Austro-Hungarian punitive expedition and the site of many atrocities committed against the local population.During the first invasion of Serbia, which the Austro-Hungarian leadership euphemistically dubbed a punitive expedition (German: Strafexpedition),[4] Austro-Hungarian forces occupied parts of Serbia for thirteen days. Their war aims were not only to eliminate Serbia as a threat but also to punish her for fuelling South Slav irredentism in the Monarchy.

 The occupation turned into a war of annihilation, accompanied by massacres of civilians and the taking of hostages.[5] Austro-Hungarian troops committed a number of war crimes against the Serbian population, especially in the area of Mačva, where according to historian Geoffrey Wawro the Austro-Hungarian army savaged the civilian population in a wave of atrocities.[6] During the short occupation between 3,500 and 4,000 Serb civilians were killed in executions and acts of random violence by marauding troops.

Mass killings took place in numerous towns in northern Serbia. On 17 August 1914, in the Serbian town of Šabac, 120 residents—mostly women, children and old men, who had previously been locked in a church—were shot and buried in the churchyard by Austro-Hungarian troops on the orders of Feldmarschall-Leutnant Kasimir von Lütgendorf.

The remaining residents were beaten to death, hanged, stabbed, mutilated or burned alive. A pit was later discovered in the village of Lešnica containing 109 dead peasants who were "bound together with a rope and encircled by wire"; they had been shot and immediately buried, even with some still alive. Wawro writes that in Krupanj, men of the 42nd Home Guard Infantry Division, the exclusively Croat formation known as the Devil's Division,[a] bashed a group of old men and boys to the ground using rifle buttstrokes and then hanged any who were still breathing.

A picture postcard showing Serbs being executed by hanging in Kruševac as Austrian soldiers pose.These types of attacks were planned at the highest level, the ground for the escalation of violence was ideologically prepared by the commanders' verbal radicalism,[8] on August 13 Potiorek ordered reprisal hangings, the taking of hostages and arson by all units. Often bodies were left hanging on the gallows, trees or street lamps for days as a deterrent and as evidence of the Austro-Hungarian military's determination to deal with Serbian suspects.[12] Many executions were photographed by Austro-Hungarian soldiers and officers; some of the images were reproduced as postcards and sold through the Austro-Hungarian army's official sales outlets. 

The Swiss criminologist and physician Archibald Reiss reported on the atrocities committed by the Austro-Hungarian army in a report that was presented at the Paris Peace Conference of 1919,[13] Reiss recorded that the number of civilians killed in the invaded Serbian territory amounted to between 3,000 and 4,000, including a large number of women and children, in the region around Šabac he counted 1,658 burned buildings. According to historian James Lyon, "the Habsburg forces engaged in an orgy of looting, rape, murder, mass extermination, and other atrocities". Reiss likened the Austro-Hungarian atrocities to the Rape of Belgium.

On 24 August, after delivering a major defeat to Austria-Hungary's invading "Balkan Armed Forces" (German: Balkanstreitkräfte) at the Battle of Cer,[11] the Royal Serbian Army liberated Šabac and reached the frontier banks of the Sava River, thereby bringing the first Austro-Hungarian invasion of Serbia to an end, and securing the first Allied victory of World War I.