The 1991 Yugoslav campaign in Croatia was an armed conflict between the Yugoslav People's Army (JNA), the Yugoslav Navy and the Yugoslav Air Force, and the Croatian National Guard (ZNG) then the Croatian Army (HV) during the Croatian War of Independence. The JNA was originally deployed in order to preserve Yugoslavia, and the initial plan of the campaign entailed the military occupation of Croatia and the removal of the Croatian leadership elected in 1990. The JNA intervention was the culmination of its involvement in the confiscation of weapons from Croatia's Territorial Defence, and in the Croatian Serb revolt that had begun in August 1990. From that time, the JNA had been frequently deployed to form a buffer zone between the Croatian Serb guerrillas and the ZNG or the Croatian police. In effect, these JNA buffer zones often secured the territorial gains of the insurgents and led to an increasingly hostile relationship between the JNA and Croatia. The JNA campaign plan was amended shortly before the campaign to include the relief of JNA barracks besieged by the ZNG. The besieging and subsequent capture of several JNA facilities allowed Croatia to arm its previously poorly equipped military and to equip and recruit new ethnic Croat conscripts and officers of the Yugoslav People's Army.
The campaign effectively started on 20 September 1991, even though relatively minor offensive actions had already been undertaken. By the end of the month, it suffered from serious delays and manpower shortages caused by low call-up turnout in Serbia. In early October, the original campaign objectives were reduced as Serbian president Slobodan Milošević and his allies gained greater control of the JNA. Subsequently, the campaign objectives were redefined to deny the Croatian Government access to parts of Croatia that contained substantial Serb populations and to protect Croatian Serbs. The campaign culminated in late November and early December with the Battle of Vukovar and the Siege of Dubrovnik. A limited Croatian counterattack and the development of the Croatian Army led to a stalemate on the battlefield.
The strategic situation permitted the development of the Vance plan—a ceasefire supervised by United Nations peacekeepers designed to create conditions for the political settlement of the conflict in Croatia. The Sarajevo Agreement, regarding the implementation of the ceasefire, was signed on 2 January 1992, bringing the campaign to an end. Nonetheless, the JNA took several more months to withdraw from Croatia as it was replaced by the UN peacekeepers. In 1991 alone, the conflict caused more than 7,000 deaths and the internal displacement of 400,000–600,000 people. More than 1,700 persons remain missing as a result of the campaign.
Background
In 1990, following the electoral defeat of the government of the Socialist Republic of Croatia, ethnic tensions increased. The Yugoslav People's Army (Jugoslovenska Narodna Armija – JNA) confiscated the weapons of Croatia's Territorial Defence (Teritorijalna obrana – TO) to minimize potential resistance. On 17 August, the tensions escalated into an open revolt by Croatian Serbs, centred on the predominantly Serb-populated areas of the Dalmatian hinterland around Knin, parts of the Lika, Kordun, Banovina regions and eastern Croatia. In January 1991, Serbia, supported by Montenegro and Serbia's provinces of Vojvodina and Kosovo, made two unsuccessful attempts to obtain approval from the Yugoslav Presidency to deploy the JNA to disarm Croatian security forces. After a bloodless skirmish between Serb Krajina Militia and Croatian special police in March, the JNA, supported by Serbia and its allies, asked the federal Presidency to grant it wartime powers and declare a state of emergency. The request was denied on 15 March, and by the summer of 1991, the JNA came under the control of the Serbian President Slobodan Milošević as the Yugoslav federation started to fall apart.
Milošević became de facto commander of the JNA once he secured control over the vacant federal presidency and through his influence over the federal defence minister General Veljko Kadijević and JNA chief of staff Blagoje Adžić. Milošević, preferring a campaign aimed at expanding Serbia rather than preserving Yugoslavia, publicly threatened to replace the JNA with a Serbian army and declared that he no longer recognized the authority of the federal presidency. This threat caused the JNA to gradually abandon plans to preserve Yugoslavia in favour of the expansion of Serbia. By the end of the month, the conflict had escalated and the first fatalities occurred. The JNA then stepped in to support the guerrillas and prevent Croatian police from intervening. In early April, leaders of the Serb revolt in Croatia declared their intention to integrate the area under their control with Serbia. The Government of Croatia considered this an act of secession.
At the beginning of 1991, Croatia had no regular army. In an effort to bolster its defence, it doubled police numbers to about 20,000. The most effective part of the force was the 3,000-strong special police deployed in 12 battalions which adopted principles of military organization. In addition, there were 9,000–10,000 regionally-organized reserve police; these were set up in 16 battalions and 10 independent companies, but the units lacked weapons. In May, in response to the deteriorating situation, the Croatian government established the Croatian National Guard (Zbor narodne garde – ZNG) by amalgamating the special police battalions into four guards brigades. The guards brigades initially comprised about 8,000 troops, and were subordinated to the Ministry of Defence headed by retired JNA General Martin Špegelj. The regional police, by then expanded to 40,000, was also attached to the ZNG and re-organized into 19 brigades and 14 independent battalions. The guards brigades were the only ZNG units that were fully equipped with small arms, while heavier weapons and an effective command and control structure were lacking throughout the ZNG. At the time, Croatian weapon stocks consisted of 30,000 small arms purchased abroad in addition to 15,000 previously owned by the police. A new 10,000-strong special police was established to replace the personnel transferred to the ZNG guards brigades.
The Croatian view of the JNA role in the Serb revolt gradually evolved between January and September 1991. The initial plan of Croatian President Franjo Tuđman was to win support for Croatia from the European Community (EC) and the United States, and he dismissed advice to seize JNA barracks and storage facilities in the country. Tuđman's stance was motivated by his belief that Croatia could not win a war against the JNA. The ZNG was limited to a defensive role even though the actions of the JNA appeared to be coordinated with Croatian Serb forces. This impression was reinforced by buffer zones the JNA established after armed conflicts between the Croatian Serb guerrillas and the ZNG—the JNA intervened after the ZNG lost ground, leaving the Croatian Serbs in control of the territory. Furthermore, the JNA provided some weapons to the Croatian Serbs, although the bulk of the weaponry was provided from Serbia's TO and Ministry of Internal Affairs stocks. After the start of the JNA intervention in Slovenia in late June, conscripts began deserting from the JNA and very few were drafted to replace them, except in Serbia.
Prelude
The JNA intervened directly against Croatia in early July in Baranja, north of the city of Osijek. On 1 August, they drove Croatian forces out of Erdut, Aljmaš and Dalj, and out of Baranja around 22 August. During the summer of 1991, the Croatian Serb military consolidated in the territory under its control. In Banovina, Glina was captured from the ZNG on 26 July. That same day, two Croatian police stations near Hrvatska Kostajnica were captured, isolating the town. The attacks, codenamed Operation Stinger, were carried out by the 7th Banija Division, spearheaded by the Knin special police led by Dragan Vasiljković. In the aftermath of capture of the Kozibrod police station, Serb forces committed the first mass killing, involving the deaths of ten captured policemen and seventeen civilians.
The ZNG successfully defended Hrvatska Kostajnica until mid-September. In August, Croatian Serbs acting under the operational control of the JNA clashed with the ZNG around Osijek, Vukovar and Vinkovci in eastern Slavonia. Fighting in eastern Slavonia led to ZNG blockades of JNA barracks in those cities and limited fighting against the garrisons there. In western Slavonia, the Croatian Serb militia attempted to advance into Daruvar but were held back by the ZNG in the area around Okučani and south of Pakrac before the JNA formed a buffer zone there. Following this fighting, Croatia was denied use of major transport routes between Zagreb and Slavonia. In northern Dalmatia, the JNA initiated several clashes with the ZNG and coordinated its advances with Croatian Serb forces. These attacks culminated in the capture of Kijevo on 26 August and the Maslenica Bridge on 11 September. The capture of the bridge severed the last remaining road link between Dalmatia and the rest of Croatia. In the summer of 1991, the performance of the ZNG was poor because it lacked manpower and weapons, and exerted inadequate command and control. The professional ZNG troops were better trained than their opponents, with the exception of the Knin special police set up by the Serbian State Security Service.
On 1 September 1991, Tuđman accepted an EC-proposed ceasefire and peace conference, despite his ultimatum demanding that the JNA return to its barracks by 31 August. After the Yugoslav Presidency also accepted it, the conference began on 7 September. Four days later, the Croatian member and chair of the federal presidency, Stjepan Mesić, ordered the JNA to return to its barracks within 48 hours. The move was motivated by Tuđman's impression that the conference would have continued endlessly while the ZNG lost ground. The order was disputed by other members of the presidency, but it gave Croatia justification to openly confront the JNA. On 14 September, the ZNG and the Croatian police blockaded and cut utilities to all JNA facilities it had access to, beginning the Battle of the Barracks. The ZNG blockaded 33 large JNA garrisons in Croatia, and numerous smaller facilities including border posts and weapons and ammunition storage depots. The ZNG quickly captured isolated facilities and depots, as well as several major JNA posts, and seized large quantities of weaponsincluding the capture of entire stocks of the JNA 32nd (Varaždin) Corps and nearly all the weapons confiscated from Croatia's TO. The JNA lost control of eight brigadesincluding one armoured and two mechanized brigades, and three artillery regimentswhile additional forces in the JNA Fifth Military District and its Military-Maritime District remained besieged. The significance of the Battle of the Barracks was reinforced by the introduction of a United Nations (UN) arms embargo on 25 September. In September, Anton Tus was appointed the Chief of the General Staff of the Armed Forces of the Republic of Croatia.
Order of battle