During World War II, the Croatian Peasant Party (Hrvatska seljačka stranka, HSS) splintered into several factions pursuing different policies and alliances. Prior to the German invasion of Yugoslavia, it was the most powerful political party among ethnic Croats, controlled the administration and police in Banovina of Croatia, and commanded two paramilitary organisations. After the successful invasion of the Kingdom of Yugoslavia in April 1941, Nazi Germany proposed that HSS leader Vladko Maček could rule Croatia as a puppet state. He declined, but the Ustaše agreed and proclaimed the Independent State of Croatia (Nezavisna država Hrvatska, NDH). Under duress, Maček called on Croats to support the regime. A splinter of the HSS and all HSS-controlled infrastructure went over to the Ustaše.