After WWI and Serbian troops taking Croatia and Slovenia, both Peter I and Alexander I are accepting idea of smaller territorial gains proposed by Prime Minister Nikola Pašić . Serbs annex whole Bosnia, parts of Slavonia inhabited with Serbs and greater part f Dalmatia.
Serbs also gave Croatians ultimatum: either they want to be incorporated fully into Serb state, or just forget about lost territories, where dialect of Croatian (Shtokavian) similar to Serbian is spoken and to create a state with Slovenians.
Slovenian Croatians create new standard of Croatian based on Kaikavian and similar to it Slovenian dialects.