Slovene middle class—sought to make Trieste "città italianissima", committing series of attacks, led by Black Shirts, on Slovene shops, libraries, lawyer offices, and the central place of the rival community in Narodni dom. Forced Italianization followed and by the mid-1930s, several thousand Slovenes, especially intellectuals from Trieste region, emigrated to the Kingdom of Yugoslavia and to South America. The present-day Slovenian municipalities of Idrija, Ajdovščina, Vipava, Kanal, Postojna, Pivka, and Ilirska Bistrica, were subjected to forced Italianization. The Slovene minority in Italy (1920-1947) lacked any minority protection under international or domestic law. Clashes between the Italian authorities and Fascist squads on one side, and the local Slovene population on the other, started as early as 1920, culminating with the burning of the Narodni dom, the Slovenian National Hall of Trieste. After all Slovene minority organizations in Italy had been suppressed, the militant anti-fascist organization TIGR was formed in 1927 in order to fight Fascist violence. The anti-Fascist guerrilla movement continued throughout the late 1920s and 1930s. When Hungary, Bulgaria and Romania joined the Tripartite pact in 1940, pressure greatly increased on Yugoslavia to join in as Hitler was trying to protect its southern flank before launching the attack on the Soviet Union. The signing of the Treaty of the Kingdom of Yugoslavia with Germany on March 25, 1941, was followed two days later by a coup led by aviation general Dušan Simović. Regent prince Pavel was thrown out and authority was granted to young Peter. General Simović took over the provisional administration of the government. Thus, Yugoslavia did not seem to be reliable anymore to Hitler, and so on April 6, 1941, according to the operation Marita and without a formal declaration of war, Axis forces invaded the Kingdom of Yugoslavia. The attack began with the bombing of Belgrade, killing 20,000 people. The resistance of the Yugoslav royal army was only symbolic, as only half of the recruits were able to collect due to slow mobilization, and the military equipment and doctrine of Serbia from the Balkan wars and the First World War were obsolete. Thus, on April 10, German troops have already reached Zagreb and on April 12 Belgrade. The Italian army launched its attack only on April 11, when Hungary joined. At that time, the German army was already in Karlovac. The Italian army split into two parts: it penetrated the part towards both Ljubljana and beyond via