The newly established Kingdom of Serbs, Croats and Slovenes participated in the Paris Peace Conference with Trumbić as the country's representative. Since the Allies had lured the Italians into the war with a promise of substantial territorial gains in exchange, which cut off a quarter of Slovene ethnic territory from the remaining three-quarters of Slovenes living in the Kingdom of SHS, Trumbić successfully vouched for the inclusion of most Slavs living in the former Austria-Hungary to be included within the borders of the new Kingdom of Serbs, Croats and Slovenes. Nevertheless, with the Treaty of Rapallo a population of half a million Slavs, mostly Slovenes, were subjected to forced Italianization until the fall of Fascism in Italy. At the time when Benito Mussolini was willing to modify the Rapallo borders in order to annex the independent state of Rijeka to Italy, Pašić's attempts to correct the borders at Postojna and Idrija were effectively undermined by the regent Alexander who preferred "good relations" with Italy.