 The Independent State of Croatia ( NDH ) was founded on 10 April 1941 , during the invasion of Yugoslavia by the Axis powers . The NDH consisted of most of modern @-@ day Croatia and Bosnia and Herzegovina , together with some parts of modern @-@ day Serbia . It was essentially an Italo – German quasi @-@ protectorate , as it owed its existence to the Axis powers , who maintained occupation forces within the puppet state throughout its existence . In the immediate aftermath of the Yugoslav surrender on 17 April , former Royal Yugoslav Army troops returned to their homes in eastern Herzegovina with their weapons . This was a significant security concern for the fledgling NDH government due to the proximity of the border with Montenegro , the close relationship between the people of eastern Herzegovina and Montenegro , and widespread <unk> in the region . On the day after the surrender , the commander of the NDH armed forces , <unk> ( Marshal ) <unk> Kvaternik issued a proclamation demanding the surrender of all weapons to NDH authorities by 24 April . 
