HSS, wanda Vladko Maček ke jagoranta, ya ci gaba da ba da shawara ga tarayyar Yugoslavia, wanda ya haifar da Yarjejeniyar Cvetković <unk> Maček na watan Agusta 1939 da kuma mulkin mallaka na Banovina na Croatia. Gwamnatin Yugoslavia ta ci gaba da kula da tsaro, tsaro na ciki, harkokin waje, kasuwanci, da sufuri yayin da wasu batutuwa suka bar Sabor na Croatia da kambi. A watan Afrilu 1941, Jamus da Italiya suka mamaye Yugoslavia. Bayan mamayewar, waɗanne sassa na Croatia, Bosnia da Herzegovina, da yankin Sirmium mai zaman kanta da Sarkin ya jagoranci, sun shiga cikin tsarin mulkin Yugoslavia. An yi amfani da yankin na Jihar Hungary da kuma arewacin Croatia bayan mamayewar mulkin Nazi na Hungary.
Sassan Dalmatia