The Yugoslavist idea has roots in the 1830s Illyrian movement in Habsburg Croatia, where a group of intellectuals saw the unity of South Slavs within the Austrian Empire or outside of it, as a protection against Germanisation and Magyarisation.
Lack of standardisation of Serbo-Croatian brought about the practice of publication of official documents in the Ekavian speech favoured in Serbia, often in Cyrillic script not normally used by the Croats or the Slovenes to write.
The KPJ adopted a formal commitment to federalism in a highly centralised state, promoting social Yugoslavism and a diversely interpreted notion of "brotherhood and unity".
[11] In mid-19th century Slovene Lands, early Slovenian nationalists felt closer to Czechs or Russians than other South Slavs, seeking solutions within a reformed framework of the Habsburg empire.
They carried out the May 1903 coup installing the Karađorđević dynasty to power and then organised nationalist actions in "unredeemed Serbian provinces" specified as Bosnia, Herzegovina, Montenegro, Old Serbia (meaning Kosovo), Macedonia, Croatia, Slavonia, Syrmia, Vojvodina, and Dalmatia.
[26] This echoed Garašanin's 1844 Načertanije – a treatise anticipating the collapse of the Ottoman Empire, calling for the establishment of Greater Serbia to pre-empt Russian or Austrian expansion into the Balkans and unifying all Serbs into a single state.
[32] Kállay's language policy coincided with the formal introduction of the orthographic norms set out in the Vienna Literary Agreement by the administration of Ban Károly Khuen-Héderváry in Croatia-Slavonia in the 1890s.
[31] In 1878–1903, strong antagonism developed between Serbs and Croats as the agendas for creation of the Greater Serbia and the Triune Kingdom clashed over the issue of Serbian or Croatian control of Bosnia and Herzegovina.
[34] Some sources also identify a group associated with the concept of Yugoslavism as the pseudo-Yugoslavs tactically choosing to pursue an apparently Yugoslavist agenda to implement specific national interests.
[38] On 28 June 1914, Gavrilo Princip – a Bosnian Serb member of the Young Bosnia movement assassinated Archduke Franz Ferdinand of Austria, heir presumptive to the throne of Austria-Hungary, in Sarajevo.
[40] The organisation, supported by the Black Hand, consisted of Yugoslavist nationalists advocating a political union of Serbs, Croats, Slavic Muslims, and Slovenes through revolutionary actions.
A committee tasked with determining war aims produced a programme to establish a Yugoslav state by adding Croatia-Slavonia, Slovene Lands, Vojvodina, Bosnia and Herzegovina, and Dalmatia.
On the other hand, the committee learned of the Treaty of London awarding the Kingdom of Italy parts of the Slovene Lands, Istria, and Dalmatia by the Triple Entente in return for an Italian alliance.
[47] In May 1917, members of the Yugoslav Deputies' Club of the Imperial Council in Vienna drafted the May Declaration on unification of Slovenes, Croats, and Serbs within Austria-Hungary and a trialist restructuring of the empire.
Starčević's faction of the SP and the Croatian People's Peasant Party (HSS) led by Stjepan Radić, supported the declaration in the Diet of Hungary where Croatia-Slavonia was represented.
In mid-November, Italian troops entered Istria, captured Rijeka on 17 November and were stopped before Ljubljana by city defenders, including a battalion of Serbian prisoners of war.
[64] In the military, use of Latin script was often regarded as reflecting anti-state sentiment and contributed to the decision by many non-Serbs to resign commissions – increasing Serb numerical domination among the officer corps.
The KPJ and the HSS – the third and the fourth largest parliamentary parties – refused to participate in the assembly over the rule that a simple majority would adopt the new constitution rather than by consensus as foreseen by the Corfu Declaration.
[90] The Vidovdan Constitution was dysfunctional and ultimately failed because it was illegitimate and did not ensure the rule of law, individual rights, neutrality of the state in the matters of religion and national culture.
[91] Interior minister Milorad Drašković cancelled the KPJ victory in the 1920 Belgrade city election, prompting the communist terrorist group Crvena Pravda to assassinate him.
[104] In 1927, the SDS and the HSS established the Peasant-Democratic Coalition [hr] (SDK) ostensibly to fight a taxation system which placed a disproportionately higher tax burden on areas not included in the pre-1918 Kingdom of Serbia.
Instead, the SDK adopted a resolution breaking off relations with Serbia-based parties and declaring they no longer recognised the Kingdom of Serbs, Croats and Slovenes – returning to advocating a republic.
As the crisis coincided with the tenth anniversary of establishment of the kingdom, Frankist leaders Ante Pavelić and Gustav Perčec [hr] portrayed Radić as the most recent in a long line of Croatian victims who suffered at the hand of Serbs in their All Saints' Day and 5 December decennial speeches.
[125] Urged by the British, French, and Czechoslovak allies and possibly influenced by the toppling of Alfonso XIII of Spain,[118] King Alexander negotiated with the NRS and the SLS to broaden his base of support – resulting in the Octroic Constitution.
It was compounded by the narrative of the Serbian World War I struggle and sacrifice – which was interpreted as implying entitlement of the Serbs to lead Yugoslavia on account of suffering to liberate all the Yugoslavs.
[156] Tito's foreign policy sought to integrate Albania into the Yugoslav federation, support the Greek communist guerrillas,[157] and broaden ties with Bulgaria–potentially uniting the countries.
This led to debates about the level of (de)centralisation and a power-struggle which increasingly equated the struggle for centralism with unitarism and Serbian interests at the expense of other Yugoslav republics.
Between 1957 and 1966, the political conflict developed with factions allied with the foreign minister, Edvard Kardelj, (a Slovene) and the Yugoslav vice-president and Tito's likely successor Aleksandar Ranković (a Serb).
[166] The intra-SKJ debate over the future of the federation took place by proxy: Dobrica Ćosić represented pro-centralisation views he attributed to leading Serbian communist Jovan Veselinov and Tito.
[204] Lacking international support for independence, the Slovene and Croatian leaderships proposed a confederal reform of Yugoslavia, but diverging circumstances made Croatian–Slovene cooperation difficult.