After the establishment of the Independent State of Croatia, all of Bosnia and Herzegovina, including the area of Bihać-Cazin Krajina, became a part of the Croatian state. In terms of administrative-territorial division, the Independent State of Croatia (NDH) consisted of great counties (Velike ţupe). One of those counties was Great County of Krbava and Psat which encompassed Bihać-Cazin Krajina, with its seat at Bihać. In this doctoral dissertation, key events of the above mentioned county from the year 1941 to 1945 were explored from the viewpoint of the NDH government of that area. Administrative-territorial division and military organization of the Great County of Krbava and Psat and the position of the county after the Chetnik-communist uprising at the end of 1941 are presented in the first part of the dissertation. Alongside the unfolding of these events, causes and effects of the Chetnik-communist uprising, which negatively impacted the civilian and military service and safety conditions in Great County of Krbava and Psat, are also discussed in this dissertation. Causes and consequences of the temporary partisan occupation of the Great County of Krbava and Psat at the beginning of November 1942 are analyzed in a specific chapter of the dissertation. This paper gives us an insight into the extent of crimes committed by partisans during their stay in the county, with the majority of victims being Catholics and Muslims. Reestablishment of the NDH government in the Great County of Krbava and Psat at the end of 1943 led to a new political and military organization of the county, with Germany having a major role. This situation continued until the NDH government retreated from the county at the end of March 1945. In addition, political circumstances, the repressive politics of NDH, economic, social, and transport conditions, as well as other major factors of NDH administration in that area, are examined. All of these events are observed in the context of military affairs and of other politico-military aspects in that area – the partisan movement, the Chetnik movement, as well as Italian and German military.