Chetniks in World War I

Chetniks in World War I were members of auxiliary units used by the Royal Serbian Army for special operations against invading Austro-Hungarian, Bulgarian and German forces.

First organised into military formations during the Balkan Wars (1912–1913), they became an integral part of the Royal Serbian Army in August 1914 with the formation of four detachments. Their primary task was to defend the borders before transitioning to operate as special forces behind enemy lines, disrupting operations and conducting diversionary tactics.

The Chetniks were engaged in action from the onset of the conflict, enduring heavy casualties in direct combat, estimated at 60% during the first Serbian Campaign. With the occupation of the country, they evolved into resistance fighters, forming new units and conducting guerrilla warfare, ultimately playing a significant role in the liberation of Serbia and Montenegro. The Serbian army was one of the first in Europe to have such guerrilla detachments in its ranks. After the war, Chetnik detachments were disbanded.

Origin
Chetnik units trace their origins to the era of the Ottoman Empire, when groups of Serbian outlaws were organised to resist Turkish occupation and later to oppose rival pro-Bulgarian factions (Bulgarian comitadjis) in Macedonia; as well as Austrian occupation in Bosnia-Herzegovina. The term "Chetnik" (Četnik ) derives from the Serbian word četa meaning band or troop. Throughout the Balkan Wars, Chetnik units played significant roles, acting as Vanguards, disrupting enemy lines, attacking communication facilities, and establishing order in liberated areas. They were coordinated by army commands and remained active even during the Second Balkan War against Bulgaria acquiring substantial guerrilla experience. Post-war, they contributed to pacification efforts, occasionally resorting to terror tactics and violence against the population, especially after the Albanian uprising in western Macedonia.

Formation
On 28 July 1914, a Special Command for volunteer units was established by the Serbian War Ministry. On 4 August, four Chetnik detachments of 2,250 men in total, were established by the Serbian Army's Supreme Command, based on the directive of the Serbian government. Each detachment, placed under the command of Serbian officers, consisted of one to three battalions, while predominantly Serbs, Chetnik units also included other South Slavs of various confessions. The Serbian army was one of the first in Europe to have such guerrilla detachments in its ranks.

The Serbian government and High Command issued a general ruling regarding Chetniks' activity, based on Chief of the General Staff Radomir Putnik’s 1911 Manual War Service. In the event of a Serbian offensive, they were to "disrupt the enemy rear, attack transport lines, and compel the enemy to disperse its forces". In the event of an Austro-Hungarian offensive, they were to incite rebellion in Habsburg's territory inhabited by Serbs, and if the enemy manage to penetrate deep in Serbia "attack the enemy rear with the greatest force", to spread fear and panic. Chetnik units were to remain in permanent contact with their army group commanders, to avoid previous experiences of disobedience and lack of coordination. The main force of the Serbian army was to be kept inland, leaving regionally based second and third levy units, supported by Chetnik detachments, to defend the borders and conduct reconnaissance. Once the direction of the main enemy advance was known, the main Serbian army was to concentrate its force and engage the enemy.

Austro-Hungarian invasions (1914)
The first Chetnik units to see action were those assigned to the defence of Belgrade on the night of 28 July 1914. During the bombardment of Belgrade, to stop Habsburg forces from crossing a railway bridge over the Sava, the Tankosić detachment dynamited it. Dušan Ðonović, a member of Jovan Babunski’s Chetnik group was one of the first casualties.

The Austro-Hungarians undertook three invasions of Serbia during the autumn of 1914. Upon crossing the Drina River from Bosnia, on the first day of the offensive, on 12 August 1914, the Austro-Hungarian Balkanstreitkräfte faced immediate opposition from Chetnik detachments and border defence troops. 500 Chetnik of the Lešnica Detachment took up defensive positions on the heights east of the river. On the first day of the offensive, Chetniks units were responsible for casualties on Austro-Hungarian first-levy troops. On 15 August, as the Fifth Army moved up the Jadar valley where it mostly encountered Chetnik resistance; the Rudnik Detachment managed to stop the Austro Hungarian 42nd Home Guard Infantry Division near Krupanj. On the 19 August Chetnik units participated in the Third Army's effort to hold Habsburg forces near Mount Cer. By 20 August, defeat at the Battle of Cer forced the Austro-Hungarians back into their territory.

On 14 September the Užice Army crossed the Drina into Bosnia with its Chetnik units, but made little headway. On 27 September 1914, Major Todorović, commander of the Zlatibor Chetnik detachment, was killed near Srebrenica, after being captured. The third Austro-Hungarian offensive took place in November and December 1914. Potiorek launched an attack from Bosnia into northwestern Serbia on 17 November, capturing Belgrade on 2 December. Putnik launched a counterattack on 3 December, forcing the Habsburg forces to retreat by 9 December. Belgrade was evacuated by the Austro-Hungarians six days later, on 15 December 1914.

Second Serbian campaign (1915)
In October 1915, the Kingdom of Serbia faced a combined invasion from Austro-Hungarian, German, and Bulgarian forces advancing from two directions. The invading armies included the Austro-Hungarian Third Army, German Eleventh Army, and Bulgarian First and Second armies, took six weeks to invade the country. Outnumbered and facing formidable opposition, the Serbian Army retreated southward towards Albania, together with the Serbian government and thousand of civilians, aiming to reach the Adriatic coast for evacuation and regrouping. The Chetnik detachments withdrew with the Serbian army via Albania to Corfu and later were transferred to the Salonika front.

Occupied Serbia (1916–1918)
The invading Central Powers forces occupied the entire territory of the Kingdom of Serbia. In the subsequent division of territories, Bulgarian occupied Serbia included Macedonia and the Morava region, reflecting Bulgarian nationalist aspirations. Austro-Hungarian occupied Serbia included Old Serbia (Serbia minus Kosovo and Macedonia) while the rest of the Kingdom was under joint Central Powers occupation. Chetnik guerrillas started organising a resistance network against both military occupations. In the mountains of the Bulgarian zone, former Serbian soldiers, hiding from the Bulgarian army, got organised into Chetnik units. In September 1916, the Serbian high command sent Chetnik commander Kosta Pećanac to organise a guerrilla uprising in the Toplica District of Bulgarian occupied Serbia. On 15 September, Pećanac landed by plane in the village of Mehane on the Radan mountain. Meeting up with local leader Kosta Vojinović, they both set up headquarters on Mount Kopaonik. Despite attempts by the Serbian Supreme Command to prevent premature large-scale guerrilla warfare, when rumors spread that the Allies had reached Skopje and the Bulgarians began conscripting all men between 18 and 45 years of age for military service in January–February 1917, the Serbs spontaneously rose in revolt. Serbian Chetniks, led by Vojinović, attacked garrisons in the region of Toplica, seizing a number of towns and villages including Prokuplje, Lebane and Kuršumlija.

The Bulgarian Supreme Command appointed Macedonia born, IMRO leader Alexander Protogerov, giving him full power to suppress the uprising. On 10 March, Protogerov issued an order to the Chetniks to surrender within five days or face execution, their homes burnt down, and their families deported. The Bulgarian army counter-attack started on 12 March, assisted by paramilitary IMRO forces under Tane Nikolov and Austro-Hungarian support. By 25 March, the insurgents had been pushed into the mountains which was followed by bloody reprisals against the civilian population, mass rapes were also perpetrated. Bulgarian soldiers killed over 20,000 Serbian civilians, primarily women, old people, and children. They deported more than 80,000 to concentration camps in Bulgaria, such as Sliven. According to the Austro-Hungarian consul, the Bulgarians burned down every village in the areas of the Toplica revolt. One infamous episode recounts the fate of the leader of the Jablanica Chetnik Detachment, Dimitrije Begović's pregnant wife and four children, tortured and killed after he refused to surrender or betray his fellow Chetnik members. On 13 January 1918, Begović chose to end his own life by detonating hidden explosives while surrounded by Bulgarian officers.

The reprisals did not stop the Chetniks and in April 1917, Pećanac's guerrillas attacked a railway station, and on 15 May, they invaded Bosilegrad before retreating to Kosovo, controlled by the Austro-Hungarians. Despite Allied efforts to open a new front in Salonika, the Serbian Army couldn't break through Bulgarian lines. After a short resurgence during the Summer of 1917 with a large battle fought in the Mount Kopaonik-Mount Jastrebac region, Pećanac disappeared again in September–October 1917. In response, the Austro-Hungarian command formed Albanian paramilitary units to hunt down the remaining Serbian rebels, as well counter-units composed of IMRO comitadjis sent from Macedonia. In October two companies of the Bulgarian 11th Infantry Regiment assisted by Bulgarian paramilitaries and one Austro-Hungarian machine-gun squad managed to track down and surround Vojnović who took his own life before they could capture him.

The following year, Serbian Chetnik units, including the survivors of the Jablanica Detachment, were again instrumental in the liberation of Serbia, as advances were made on the Salonika front.

Chetnik detachments after 1915

 * Toplica-South Morava (Central) Detachment, commanded by Kosta Pećanac
 * Jablanica Detachment, commanded by Milinko Vlahović, then Dimitrije Begović
 * Tulare battalion, commanded by Milan Đurović
 * Second Jablanica battalion, commanded by Ivan Plavšić
 * Retkocer battalion,
 * Gajtan Detachment
 * Medveđa Detachment
 * Ibar-Kopaonik Detachment, commanded by Kosta Vojinović
 * Pirot Detachment, commanded by Jovan Radović
 * Krajina Detachment

Casualties and disbandment
Chetnik units sustained losses of around 60% of their forces, their use in direct frontal combat often led to devastating casualties, prompting some historians to suggest that they were sacrificed. In July 1914, prior to the invasion, the Habsburg army determined that Serb Chetniks, or Komitadjis, as the Austro-Hungarians called them, were "outside international law" and were to be "completely wiped out". The Chetniks' mixed attire, part military, part civilian, was used by the Austro-Hungarians to revive the existing myth of franc-tireurs, civilians acting as combatants, resulting in reprisals, and often war crimes, against the Serbian civilian populations. In Šabac, in retaliation for Chetnik activities, Austro-Hungarian troops executed between one hundred and two hundred civilians.

On 13 August, the Balkanstreitkräfte's Commander in Chief, General Potiorek ordered all units to seize hostages, carry out reprisal hangings, and engage in arson as part of a punitive strategy, in retaliation for Chetnik raids. In 1917, Adolf von Rhemen, the Military governor of Austro-Hungarian occupied Serbia, ordered their "ruthless extermination".

The Austro-Hungarian army also employed auxiliary troops, dressed in civilian clothing and consisting of irregular detachments from Bosnia. One such unit accompanied the 42nd Home Guard Infantry Division during the crossing into Serbia, pillaging and burning villages around Zvornik. In August 1914, sentries from the 21st Division mistook members of the paramilitary Schutzkorps for the enemy and opened fire. This confusion arose because the Schutzkorps did not wear a uniform; looked and sounded like Serbian Chetniks, identified only by their black-yellow armbands.

Just before the armistice, orders were given to dissolve the Chetnik detachments. Some of the men were absorbed into regular army units, while others were allowed to return home.