A coup d'état took place on 27 March 1941 in Belgrade, Kingdom of Yugoslavia, when the regency led by Prince Paul of Yugoslavia was overthrown and King Peter II assumed full monarchical powers. The coup was planned and conducted by a group of pro-Western Serbian nationalist Royal Yugoslav Air Force officers formally led by the Air Force commander, General Dušan Simović, who had been associated with several putsch plots from 1938 onwards. Brigadier General of Military Aviation Borivoje Mirković, Major Živan Knežević of the Yugoslav Royal Guards, and his brother Radoje Knežević were the main organisers of the overthrow of the government. In addition to Radoje Knežević, some other civilian leaders were probably aware of the plot before it was launched and moved to support it once it occurred, but they were not among the organisers. Peter II himself was surprised by the coup, and heard of the declaration of his coming-of-age for the first time on the radio.
The Communist Party of Yugoslavia played no part in the coup, although it made a significant contribution to the mass street protests in many cities that signalled popular support for it. The putsch was successful and deposed the three-member Yugoslav regency (Prince Paul, Radenko Stanković and Ivo Perović) and the government of Prime Minister Dragiša Cvetković. Two days prior to its ousting, the Cvetković government had signed the Vienna Protocol on the accession of Yugoslavia to the Tripartite Pact (Axis). The coup had been planned for several months, but the signing of the pact spurred the organisers to carry it out, encouraged by the British Special Operations Executive.
The military conspirators brought to power the 17-year-old King Peter II (whom they declared to be of age to assume the throne) and formed a weak and divided national unity government with Simović as prime minister and Vladko Maček and Slobodan Jovanović as his vice-premiers. The coup led directly to the German-led Axis invasion of Yugoslavia in April 1941. The importance of the putsch and subsequent invasion in delaying Operation Barbarossa, the Axis invasion of the Soviet Union (which started on 22 June 1941), is still open to debate. In 1972 military historian Martin van Creveld dismissed the idea, affirming that the invasion of Yugoslavia actually assisted and hastened the overall Balkan campaign, and that other factors determined the start date for Operation Barbarossa. Other academics have asserted that the invasion of Yugoslavia contributed to a delay in the launching of Operation Barbarossa.
Background
The Kingdom of Yugoslavia, formed in 1918 under the name Kingdom of Serbs, Croats and Slovenes, incorporated diverse national and religious groups with varied historical backgrounds. These included Serbs, Croats, Slovenes, Montenegrins, Bosnian Muslims, Macedonians and Albanians, among others. Each of these national groups was strongly associated with one of the three dominant religions: the Serbian Orthodox Church (Serbs, Montenegrins and Macedonians); the Catholic Church (Croats and Slovenes); and Islam (Bosnian Muslims and Albanians). The religious diversity deepened the divisions within Yugoslav society. Serbs and Montenegrins made up 38.8 per cent of the population, Croats contributed 23.9 per cent, Slovenes 8.5 per cent, Bosnian Muslims 6.3 per cent, Macedonians 5.3 per cent, and Albanians 4 per cent.
According to economics professor and historian Jozo Tomasevich, Yugoslavia was politically weak from the moment of its creation and remained so during the interwar period mainly due to a "rigid system of centralism" imposed by the Serb-friendly Vidovdan Constitution, the aforementioned strong association between each national group and its dominant religion, and uneven economic development. In particular, the religious primacy of the Serbian Orthodox Church in national affairs and discrimination against Catholics and Muslims compounded the dissatisfaction of the non-Serb population with the Serb-dominated ruling groups that controlled patronage and government appointments, and treated non-Serbs as second-class citizens. This centralised system arose from Serb military strength and Croatian intransigence, and was sustained by Croat disengagement, Serb overrepresentation, corruption, and a lack of discipline within political parties. This state of affairs was initially maintained by subverting the democratic system of government through political bribery. The domination of the rest of Yugoslavia by Serb ruling elites meant that the country was never consolidated in the political sense, and was therefore never able to address the social and economic challenges it faced.
The political scientist Sabrina P. Ramet sees the dysfunctionality and lack of legitimacy of the regime as the reasons why the kingdom's internal politics became ethnically polarised, a phenomenon that has been referred to as the "national question" in Yugoslavia. Failures to establish the rule of law, to protect individual rights, to build tolerance and equality, and to guarantee the neutrality of the state in matters relating to religion, language and culture contributed to this illegitimacy and the resulting instability.
In 1929, democracy was abandoned and a royal dictatorship was established by King Alexander, who attempted to break down the ethnic divisions in the country through various means, including creating administrative divisions (Serbo-Croatian Latin: banovine) based on rivers rather than traditional regions. There was significant opposition to this move, with Serbian and Slovene opposition parties and figures advocating the division of Yugoslavia into six ethnically based administrative units. By 1933, discontent in the largely Croat-populated Sava Banovina had developed into full-blown civil disorder, which the regime countered with a series of assassinations, attempted assassinations and arrests of key Croat opposition figures including the leader of the Croatian Peasant Party (Serbo-Croatian Latin: Hrvatska seljačka stranka, HSS) Vladko Maček. When Alexander was assassinated in Marseille in 1934 by a Bulgarian assassin with links to the Croat ultranationalists, the Ustaše, his cousin Prince Paul headed a triumvirate regency whose other members were the senator Radenko Stanković and the governor of the Sava Banovina, Ivo Perović. The regency ruled on behalf of Alexander's 11-year-old son, King Peter, but the important member of the regency was Prince Paul. Although Prince Paul was more liberal than his cousin, the dictatorship continued uninterrupted. The dictatorship had allowed the country to follow a consistent foreign policy, but Yugoslavia needed peace at home in order to assure peace with its neighbours, all of whom had irredentist designs on its territory.
Yugoslav foreign policy during the interwar period
From 1921, the country had negotiated the Little Entente with Romania and Czechoslovakia in the face of Hungarian designs on its territory, and after a decade of bilateral treaties, had formalised the arrangements in 1933. This had been followed the next year by the Balkan Pact of Yugoslavia, Greece, Romania and Turkey, aimed at thwarting Bulgarian aspirations. Throughout this period, the Yugoslav government had sought to remain good friends with France, seeing her as a guarantor of European peace treaties. This was formalised through a treaty of friendship signed in 1927. With these arrangements in place, Italy posed the biggest problem for Yugoslavia, funding the anti-Yugoslav Internal Macedonian Revolutionary Organisation which promoted Bulgarian irredentism. Attempts by King Alexander to negotiate with Benito Mussolini fell on deaf ears, and after Alexander's assassination, nothing of note happened on that front until 1937. In the aftermath of Alexander's assassination, Yugoslavia was isolated both militarily and diplomatically, and reached out to France to assist its bilateral relationship with Italy. With the appointment of Milan Stojadinović as prime minister in 1935, Germany and Yugoslavia became more closely aligned. The trade relationship between the two countries also developed considerably, and Germany became Yugoslavia's most important trading partner.
Cvetković–Maček Agreement
Prince Paul recognised the lack of national solidarity and political weakness of his country, and after he assumed power he made repeated attempts to negotiate a political settlement with Maček, the leader of the dominant Croat political party in Yugoslavia, the HSS. In January 1937, Stojadinović met with Maček at Prince Paul's request, but Stojadinović was unwilling or unable to grapple with the issue of Croat dissatisfaction with a Yugoslavia dominated by the Serb ruling class. In 1938, the Anschluss brought the Third Reich to the borders of Yugoslavia, and early elections were held in December. In this background, the Royal Yugoslav Air Force (VVKJ) commander, General Dušan Simović, had been involved in two coup plots in early 1938 driven by Serb opposition to the Concordat with the Vatican, and another coup plot following the December election.
In the December 1938 Yugoslavian parliamentary election, the United Opposition led by Maček had attracted 44.9 per cent of the vote, but due to the electoral rules by which the government parties received 40 per cent of the seats in the National Assembly before votes were counted, the opposition vote only translated into 67 seats out of a total of 373. On 3 February 1939, the Minister of Education, Bogoljub Kujundžić, made a nationalist speech in the Assembly in which he stated that "Serb policies will always be the policies of this house and this government." Head of the Yugoslav Muslim Organization (JMO) Mehmed Spaho asked Stojadinović to disavow the statement, but he did not. At the behest of the Senate leader, the Slovene Anton Korošec, that evening five ministers resigned from the government, including Korošec. The others were Spaho, another JMO politician Džafer Kulenović, the Slovene Franc Snoj, and the Serb Dragiša Cvetković.
Stojadinović sought authority from Prince Paul to form a new cabinet, but Korošec as head of the Senate advised the prince to form a new government under Cvetković. Prince Paul dismissed Stojadinović and appointed Cvetković in his place, with a direction that he reach an agreement with Maček. While these negotiations were ongoing, Italy invaded Albania, Yugoslavia's southern neighbour. In August 1939, the Cvetković–Maček Agreement was concluded to create the Banovina of Croatia, which was to be a relatively autonomous political unit within Yugoslavia. Separatist Croats considered the Agreement did not go far enough, and many Serbs believed it went too far in giving power to Croats. The Cvetković-led cabinet formed in the wake of the Agreement was resolutely anti-Axis, but remained on friendly terms with Germany, and included five members of the HSS, with Maček as deputy Prime Minister. General Milan Nedić was Minister of the Army and Navy. After the outbreak of World War II in September 1939, German pressure on the government resulted in the resignation in mid-1940 of the Minister of the Interior, Stanoje Mihaldžić, who had been organising covert anti-Axis activities. In October 1940, Simović was again approached by plotters planning a coup but he was non-committal. From the outbreak of war British diplomacy focused on keeping Yugoslavia neutral, which the Ambassador Ronald Ian Campbell apparently still believed possible.
Pressure builds
By the time of the German invasion of Poland and subsequent outbreak of war in September 1939, the Yugoslav Intelligence Service was cooperating with British intelligence agencies on a large scale across the country. This cooperation, which had existed to a lesser extent during the early 1930s, intensified after the Anschluss. These combined intelligence operations were aimed at strengthening Yugoslavia and keeping her neutral while encouraging covert activities. In mid to late 1940, British intelligence became aware of coup plotting, but managed to side-track the plans, preferring to continue working through Prince Paul. The Special Operations Executive (SOE) office in Belgrade went to significant lengths to support the opposition to the anti-Axis Cvetković government, which undermined the hard-won balance in Yugoslav politics that that government represented. SOE Belgrade was entangled with pro-Serb policies and interests, and disregarded or underestimated warnings from SOE and British diplomats in Zagreb, who better understood the situation in Yugoslavia as a whole.
Yugoslavia's situation worsened in October 1940 when Italy invaded Greece from Albania, and the initial failure of the Italians to make headway only increased Yugoslav apprehension that Germany would be forced to help Italy. In September and November 1940 respectively, Germany forced Hungary and Romania to accede to the Tripartite Pact. In early November 1940, following the Italian invasion of Greece, Nedić stated in a memorandum to Prince Paul and the government that he believed that Yugoslavia was about to be fully encircled by enemy countries and that ultimately Germany would win the war. Nedić proposed to the government that it abandon its neutral stance and join the Axis as soon as possible in the thinking that joining the Axis would protect Yugoslavia against its "greedy neighbors". A few days later Prince Paul, having realised the impossibility of following Nedić's advice, replaced him with the ageing and compliant General Petar Pešić. At the same time, Adolf Hitler, recalling Serbia's excellent military performance in the Balkan Wars and World War I, was concerned that the Royal Yugoslav Army was strong, and defeating it would necessitate the expenditure of considerable effort. Despite this, he remained concerned about the threat to the southern flank of his planned invasion of the Soviet Union posed by Greece and Yugoslavia, and aimed for a political resolution of Yugoslavia's status.