The project has sound theoretical background in – first – existing results of historical science dealing with this topics, and – second – justified need to enlarge the existing knowledge with new researches whose results will give important new insights of the Croatian 20th century history. In this case we will research the experience of totalitarian-authoritarian system in Croatian history of the mentioned period and how these systems used violence against individuals and certain groups of population and what was the fate and experience of those who were subjected to such violence. Research problems consist in the analysis and synthesis of vast amount of new sources. The problems will possibly also appear during the critical analysis of questionable data, especially concerning the unfounded estimates of structure and number of victims/casualties during World War II. We consider that this project has substantial importance for the historical science of Croatian 20th century. With this project Croatian historical science will received numerous new insights. Part of the project is dedicated to the research of period after 1945 which is partially completely unexplored. Therefore, this project will for the first time open certain research topics. The project could also have positive results on the society. Various discussion concerning the heritage