The Axis powers began their invasion of the Kingdom of Yugoslavia on 6 April 1941. Just four days later, a puppet state known as the Independent State of Croatia ( – NDH) was declared, encompassing most of modern-day Croatia, Bosnia and Herzegovina and parts of modern-day Serbia. In accordance with the Treaties of Rome signed by the Ustaše leadership of the NDH, a large part of the Croatian coastline and islands, including the city of Split were incorporated into the Kingdom of Italy. The low morale of Yugoslav troops in Split and the uncontested advance of the Italian Army through Dalmatia resulted in a number of desertions. Paramilitary formations of the Croatian Peasant Party (, HSS) disarmed soldiers. By 11 April, there were no organized military formations remaining in Split, and a large number of police and gendarmerie switched their allegiance to the NDH. With Split under the control of the new Ustaše government, the authorities apprehended 300 citizens they deemed to be political enemies. On 13 April, members of the League of Communist Youth of Yugoslavia (, SKOJ) broke into a number of Ustaše weapons depots, stealing dozens of rifles and machine guns, as well as ammunition and hand grenades.