autonomous party within the Communist Party of Yugoslavia. Between 1938 and 1941, left liberal, Christian left and agrarian forces established close relations with members of the illegal Communist party, aiming at establishing a broad anti-Fascist coalition. The main territory of Slovenia, being the most industrialized and westernized among others less developed parts of Yugoslavia became the main center of industrial production: in comparison to Serbia, for example, in Slovenia the industrial production was four times greater and even twenty-two times greater than in Yugoslav Macedonia. The interwar period brought a further industrialization in Slovenia, with a rapid economic growth in the 1920s followed by a relatively successful economic adjustment to the 1929 economic crisis. This development however affected only certain areas, especially the Ljubljana Basin, the Central Sava Valley, parts of Slovenian Carinthia, and the urban areas around Celje and Maribor. Tourism experienced a period of great expansion, with resort areas like Bled and Rogaška Slatina gaining an international reputation. Elsewhere, agriculture and forestry remained the predominant economic activities. Nevertheless, Slovenia emerged as one of the most prosperous and economically dynamic areas in Yugoslavia, profiting from a large Balkan market. Arts and literature also prospered, as did architecture. The two largest Slovenian cities, Ljubljana and Maribor, underwent an extensive program of urban renewal and modernization. Architects like Jože Plečnik, Ivan Vurnik and Vladimir Šubic introduced modernist architecture to Slovenia. Fascist Italianization of Littoral Slovenes and resistance With a secret Treaty of London in 1915, the Kingdom of Italy was promised large portions of Austrian-Hungarian territory by the Triple Entente, in exchange for joining the Entente against the Central Powers in World War I. After the Central Powers were defeated in 1918, Italy went on to annex some of the promised territories, after signing the treaty of Rapallo with the new Kingdom of Serbs, Croats and Slovenes in 1920. However, these areas also included a quarter of Slovene ethnic territory and approximately 327.000 out of total population of 1.3 million Slovenes, were annexed by the Kingdom of Italy The treaty left half a million Slavs (besides Slovenes also Croatians) inside Italy, while only a few hundred Italians in the fledgling Yugoslav state". Trieste was at the end of 19th century de facto the largest Slovene city, having had more Slovene inhabitants than even Ljubljana. After being ceded from the multi-ethnic Austria, Italian lower middle class—who felt most threatened by the city's