A coup d'état occurred on 27 March 1941 in Belgrade. The coup was planned and conducted by a group of pro-Western Serb-nationalist Royal Yugoslav Air Force and Royal Guard officers formally led by Simović. For practical purposes several others performed leadership roles in the conduct of the coup. Some other civilian leaders were probably aware of the coup before it was launched and moved to support it once it occurred, but they were not among the organisers. The Communist Party of Yugoslavia played no part in the coup, although it made a significant contribution to the mass street protests in many cities that signalled popular support for the coup after it occurred. The coup was successful and overthrew the three-member regency as well as the government of Cvetković. The coup had been planned for several months, but the signing of the Tripartite Pact spurred the organisers to carry it out, encouraged by the SOE. The military conspirators brought to power the 17-year-old king, whom they declared to be of age to assume the throne, and a government of national unity was formed with Simović as prime minister and Maček and Slobodan Jovanović as his vice-premiers.