The Yugoslav Partisans,Serbo-Croatian, Macedonian, and Slovene: , officially the National Liberation Army and Partisan Detachments of Yugoslavia; ; (often shortened as the National Liberation Army; ; ) was the communist-led anti-fascist resistance to the Axis powers (chiefly Nazi Germany) in occupied Yugoslavia during World War II. Led by Josip Broz Tito, the Partisans were Europe's most effective anti-Axis resistance movement during World War II.

Primarily a guerrilla force at its inception, the Partisans developed into a large fighting force engaging in conventional warfare later in the war, numbering around 650,000 in late 1944 and organized in four field armies and 52 divisions. The main stated objectives of the Partisans were the liberation of Yugoslav lands from occupying forces and the establishment of a communist-ruled Yugoslav state.

The Partisans were organized on the initiative of Tito following the Axis invasion of Yugoslavia in April 1941, and began an active guerrilla campaign against occupying forces after Germany invaded the Soviet Union in June. A large-scale uprising was launched in July, later joined by Draža Mihailović's Chetniks; this led to the creation of the short-lived Republic of Užice. The Axis mounted a series of offensives in response but failed to completely destroy the highly mobile Partisans and their leadership. By late 1943, the Allies had shifted their support from Mihailović to Tito as the extent of Chetnik collaboration became evident, and the Partisans received official recognition at the Tehran Conference. In Autumn 1944, the Partisans and the Soviet Red Army liberated Belgrade following the Belgrade Offensive. By the end of the war, the Partisans had gained control of the entire country as well as Trieste and Carinthia. After the war, the Partisans were reorganized into the regular armed force of the newly established Federal People's Republic of Yugoslavia.

Objectives

One of two objectives of the movement, which was the military arm of the Unitary National Liberation Front (UNOF) coalition, led by the Communist Party of Yugoslavia (KPJ) and represented by the Anti-Fascist Council for the National Liberation of Yugoslavia (AVNOJ), the Yugoslav wartime deliberative assembly, was to fight the occupying forces. Until British supplies began to arrive in appreciable quantities in 1944, the occupiers were the only source of arms. The other objective was "to establish a communist-ruled Yugoslav state." To this end, the KPJ attempted to appeal to the various ethnic groups within Yugoslavia, by preserving the rights of each group.

The objectives of the rival resistance movement, the Chetniks, were the retention of the Yugoslav monarchy, ensuring the safety of ethnic Serb populations, and the establishment of a Greater Serbia through the ethnic cleansing of non-Serbs from territories they considered rightfully and historically Serbian.: "From the summer of 1941, the Chetniks increasingly gained control over Serb insurgents and carried out gruesome crimes against Muslims of eastern Bosnia-Herzegovina. Massacres of Muslims, usually by cutting the throats of the victims and tossing the bodies into various water-ways, occurred especially in eastern Bosnia, in Foča, Goražde, Čajniče, Rogatica, Višegrad, Vlasenica, Srebrenica, all in the basin of the Drina river, but also in eastern Herzegovina, where individual villages resisted Serb encirclement with ferocious determination until 1942. Chetnik documents – for example the minutes of the Chetnik conference in Javorine, district of Kotor Varoš, in June 1942 – speak of a determination to 'cleanse Bosnia of everything that is not Serb'. It is difficult to estimate the number of Muslim victims of this original ethnic cleansing, but it can be counted in the tens of thousands." Relations between the two movements were uneasy from the start, but from October 1941 they degenerated into full-scale conflict. To the Chetniks, Tito's pan-ethnic policies seemed anti-Serbian, whereas the Chetniks' royalism was anathema to the communists. In the early part of the war Partisan forces were predominantly composed of Serbs. In that period names of Muslim and Croat commanders of Partisan forces had to be changed to protect them from their predominantly Serb colleagues.

After the German retreat forced by the Soviet-Bulgarian offensive in Serbia, North Macedonia, and Kosovo in the autumn of 1944, the conscription of Serbs, Macedonians, and Kosovar Albanians increased significantly. By late 1944, the total forces of the Partisans numbered 650,000 men and women organized in four field armies and 52 divisions, which engaged in conventional warfare. By April 1945, the Partisans numbered over 800,000.

Name The movement was consistently referred to as the "Partisans" throughout the war. However, due to frequent changes in size and structural reorganizations, the Partisans throughout their history held four full official names (translated here from Serbo-Croatian to English): National Liberation Partisan Detachments of Yugoslavia; ; (June 1941 – January 1942) National Liberation Partisan and Volunteer Army of Yugoslavia; ; (January – November 1942) National Liberation Army and Partisan Detachments of Yugoslavia (November 1942 – February 1945). Increasingly from November 1942, the Partisan military as a whole was often referred to simply as the National Liberation Army (Narodnooslobodilačka vojska, NOV), whereas the term "Partisans" acquired a wider sense in referring to the entire resistance faction (including, for example, the AVNOJ). Yugoslav Army; ; – on 1 March 1945, the National Liberation Army was transformed into the regular armed forces of Yugoslavia and renamed accordingly. The movement was originally named National Liberation Partisan Detachments of Yugoslavia (Narodnooslobodilački partizanski odredi Jugoslavije, NOPOJ) and held that name from June 1941 to January 1942. Because of this, their short name became simply the "Partisans" (capitalized), and stuck henceforward (the adjective "Yugoslav" is used sometimes in exclusively non-Yugoslav sources to distinguish them from other partisan movements).

Between January 1942 and November 1942, the movement's full official name was briefly National Liberation Partisan and Volunteer Army of Yugoslavia (Narodnooslobodilačka partizanska i dobrovoljačka vojska Jugoslavije, NOP i DVJ). The changes were meant to reflect the movement's character as a "volunteer army".

In November 1942, the movement was renamed into the National Liberation Army and Partisan Detachments of Yugoslavia (Narodnooslobodilačka vojska i partizanski odredi Jugoslavije, NOV i POJ), a name which it held until the end of the war. This last official name is the full name most associated with the Partisans, and reflects the fact that the proletarian brigades and other mobile units were organized into the National Liberation Army (Narodnooslobodilačka vojska). The name change also reflects the fact that the latter superseded in importance the partisan detachments themselves.

Shortly before the end of the war, in March 1945, all resistance forces were reorganized into the regular armed force of Yugoslavia and renamed Yugoslav Army. It would keep this name until 1951, when it was renamed the Yugoslav People's Army.

Background and origins

On 6 April 1941, the Kingdom of Yugoslavia was invaded from all sides by the Axis powers, primarily by German forces, but also including Italian, Hungarian and Bulgarian formations. During the invasion, Belgrade was bombed by the Luftwaffe. The invasion lasted little more than ten days, ending with the unconditional surrender of the Royal Yugoslav Army on 17 April. Besides being hopelessly ill-equipped when compared to the Wehrmacht, the Army attempted to defend all borders but only managed to thinly spread the limited resources available.

The terms of the capitulation were extremely severe, as the Axis proceeded to dismember Yugoslavia. Germany occupied the northern part of Drava Banovina (roughly modern-day Slovenia), while maintaining direct military occupation of a rump Serbian territory with a puppet government. The Independent State of Croatia (NDH) was established under German direction, which extended over much of the territory of today's Croatia and as well contained all the area of modern-day Bosnia and Herzegovina and Syrmia region of modern-day Serbia. Mussolini's Italy occupied the remainder of Drava Banovina (annexed and renamed as the Province of Lubiana), much of Zeta Banovina and large chunks of the coastal Dalmatia region (along with nearly all its Adriatic islands). It also gained control over the newly created Italian governorate of Montenegro, and was granted the kingship in the Independent State of Croatia, though wielding little real power within it. Hungary dispatched the Hungarian Third Army and occupied and annexed the Yugoslav regions of Baranja, Bačka, Međimurje and Prekmurje. Bulgaria, meanwhile, annexed nearly all of Macedonia, and small areas of eastern Serbia and Kosovo. The dissolution of Yugoslavia, the creation of the NDH, Italian governorate of Montenegro and Nedic's Serbia and the annexations of Yugoslav territory by the various Axis countries were incompatible with international law in force at that time.

The occupying forces instituted such severe burdens on the local populace that the Partisans came not only to enjoy widespread support but for many were the only option for survival. Early in the occupation, German forces would hang or shoot indiscriminately, including women, children and the elderly, up to 100 local inhabitants for every one German soldier killed. While these measures for suppressing communist-led resistance were issued in all German-occupied territory, they were only strictly enforced in Serbia. Two of the most significant atrocities by the German forces were the massacre of 2,000 civilians in Kraljevo and 3,000 in Kragujevac. The formula of 100 hostages shot for every German soldier killed and 50 hostages shot for every wounded German soldier was cut in one-half in February 1943 and removed altogether in the fall of that same year.

Furthermore, Yugoslavia experienced a breakdown of law and order, with collaborationist militias roaming the countryside terrorizing the population. The government of the puppet Independent State of Croatia found itself unable to control its territory in the early stages of the occupation, resulting in a severe crackdown by the Ustaše militias and the German army.

Amid the relative chaos that ensued, the Communist Party of Yugoslavia moved to organize and unite anti-fascist factions and political forces into a nationwide uprising. The party, led by Josip Broz Tito, was banned after its significant success in the post-World War I Yugoslav elections and operated underground since. Tito, however, could not act openly without the backing of the USSR, and as the Molotov–Ribbentrop pact was still in force, he was compelled to wait.

Formation and early rebellion During the April invasion of Yugoslavia, the leadership of the Communist Party was in Zagreb, together with Josip Broz Tito. After a month, they left for Belgrade. While the Molotov–Ribbentrop Pact between Germany and the Soviet Union was in effect, the communists refrained from open conflict with the new regime of the Independent State of Croatia. In these first two months of occupation, they extended their underground network and began amassing weapons. In early May 1941, a so-called May consultations of Communist Party officials from across the country, who sought to organize the resistance against the occupiers, was held in Zagreb. In June 1941, a meeting of the Central Committee of KPJ was also held, at which it was decided to start preparations for the uprising.Davor Marijan, The May Deliberations of the Central Committee of the Communist Party of Yugoslavia, Hrvatski institut za povijest, 2003, pp. 325–331,