The word of Yugoslavia originally means a South Slavic country. It was established in December 1918 by the unification of the two states. One is the Kingdom of Serbia, and another is the state of the Slovenes, Croats, and Serbs. The latter is an ad hoc state that the Habsburg' South Slavs founded after the breakup of the Austro-Hungarian Empire. However, there was a latent disagreement among the South Slavic political leaders on which way they should integrate the two states. To put it simply, there were two models of unification. One is to make a federal state and another is to merge the South Slavs' state into Serbia. The former was the idea of the Habsburg' South Slavs, and the latter was that of Serbians'. The fatal problem was that the representatives of the Habsburg' South Slavs did not negotiate a unification treaty with Serbian government. They took for granted that the autonomy of the local government in the former Austro-Hungarian countries was guaranteed. But the Serbian leaders did not think that they made such a promise. The ethnic dissension among the South Slavs after the unification, particularly the antagonism between the Serbs and Croats, started with the first two years of governance by an overwhelmingly Serb administration. The government had pursued a cruel suppression policy towards antigovernment movements, so that they poisoned Serbo-Croatian relations from the very outset of Yugoslavia's experiment. However, there was an effort to reverse the ominous polarization of Serbs and Croats, endowing Yugoslavia with a viable political system. The first striking attempt was the establishment of a coalition government composed of the Davidvi?'s Serbian Democrats, Spaho's Bo?njak Muslims, and Koro?ec's Slovene Populists, supported by Radi?'s Croatian Republican Peasant Party. Unfortunately this government, priding itself as a government of reconciliation was collapsed soon by antiparliamentary method, though it had a parliamentary majority. It had three points of weakness. F