In November, 1933, King Carol II asked Duca to head the government as prime minister in preparation for the December elections. In this capacity, Duca worked to keep the rising support for the Iron Guard, also known as The Legion of the Archangel Michael, a fascist movement led by Corneliu Zelea Codreanu, in check, even outlawing the All for the Fatherland-party, which was their political arm. What followed was a time of violence when police on orders from Duca sometimes attacked Iron Guard-members (which led to the deaths of some of the members) and jailed thousands of them. Shortly after these events and the release of many of the Iron Guard-members from jail, Duca was shot to death, as a form of revenge, on the platform of the Sinaia train station by Nicolae Constantinescu accompanied by two other persons. All three of them were sentenced to jail for the murder.