Caldas da Rainha is a medium-sized Portuguese city in the Oeste region, in the historical province of Estremadura, and in the district of Leiria. The city serves as the seat of the larger municipality of the same name and of the Comunidade Intermunicipal do Oeste. At the 2011 census, the municipality had a population of 51,729 in an area of 255.69 square kilometres (98.72 sq mi), with 30,343 residing in the city. Although the city itself lies about 10.5 kilometres (6.5 mi) inland, three of the municipality's civil parishes lie on the Atlantic Ocean. Caldas da Rainha is best known for its sulphurous hot springs and ceramic pottery.

The Carnation Revolution, also known as the 25 April, was a military coup by military officers that overthrew the authoritarian Estado Novo government on 25 April 1974 in Lisbon, producing major social, economic, territorial, demographic, and political changes in Portugal and its overseas colonies through the Processo Revolucionário Em Curso. It resulted in the Portuguese transition to democracy and the end of the Portuguese Colonial War.