Carnation Revolution: A leftist military coup in Portugal overthrows the authoritarian-conservative Estado Novo regime.

The Carnation Revolution, code-named Operation Historic Turn, also known as the April 25th, was a military coup in Portugal by officers that overthrew the Estado Novo regime on 25 April 1974. The coup produced major social, economic, territorial, demographic, and political changes in the European country and its overseas colonies through the Ongoing Revolutionary Process. It resulted in the Portuguese transition to democracy and the end of the Portuguese Colonial War.

A coup d'état, or simply a coup, is typically an illegal and overt attempt by a military organization or other government elites to unseat an incumbent leadership. A self-coup is said to take place when a leader, having come to power through legal means, tries to stay in power through illegal means.

The Estado Novo was the corporatist Portuguese state installed in 1933. It evolved from the Ditadura Nacional formed after the coup d'état of 28 May 1926 against the unstable First Republic. Together, the Ditadura Nacional and the Estado Novo are recognised by historians as the Second Portuguese Republic. The Estado Novo, greatly inspired by conservative and autocratic ideologies, was developed by António de Oliveira Salazar, who was President of the Council of Ministers from 1932 until illness forced him out of office in 1968.