The Banovina came to an end together with Kingdom of Yugoslavia, following the invasion by Axis powers in April 1941. Šubašić joined Dušan Simović and his Yugoslav government-in-exile but, before leaving, he refused to authorise the release of a large number of Croatian Communists and leftists arrested and kept in prisons under his supervision. Those prisons were soon taken over by the newly formed Independent State of Croatia and its prisoners were later executed by the Ustaše[citation needed].