The PIDE or International and State Defense Police (Portuguese: Polícia Internacional e de Defesa do Estado) was a Portuguese security agency that existed during the Estado Novo regime of António de Oliveira Salazar. Formally, the main roles of the PIDE were the border, immigration and emigration control and internal and external State security. However, it became more known by its political police activities.
The agency that would later become the PIDE was established by the Decree-Law 22992 of August 1933, as the Surveillance and State Defense Police or PVDE. It resulted from the merger of two former agencies, the Portuguese International Police and the Political and Social Defense Police. The PVDE was transformed into the PIDE in 1945. PIDE was itself transformed into the Directorate-General of Security or DGS in 1968. After the 25 April 1974 Carnation Revolution, DGS was disbanded in Portugal, but continued to exist transitionally in the Portuguese overseas territories as the Military Information Police or PIM, being finally completely disbanded in 1975.
Although the acronym PIDE was only formally used from 1945 to 1969, the set of successive secret polices that existed during the 40 years of the Estado Novo regime are commonly referred to as the PIDE. Historically, this set of police agencies is also often referred as PIDE/DGS, from the acronyms of its two last designations. It is referred in this last way in article 293 of the Portuguese Constitution, which states the criminalisation and judgment of its former officers.
During its existence, the organisation was known for its actions during the Spanish Civil War, its role as a political police, its counter-espionage activities during World War II and its counter-insurgency operations in the Portuguese Colonial War.
How did people know there was a revolution?
This is a translation of the radio announcement on April 25th, 1974:
"The Portuguese Armed Forces appeal to all the inhabitants of Lisbon to stay at home and to remain as calm as possible. We sincerely hope that the seriousness of the hour will not be saddened by personal injuries.
"We therefore appeal to the good sense of all military commanders to avoid any confrontation with the Armed Forces. Apart from being unnecessary, such action would only create or aggravate serious divisions between Portuguese people, which must be avoided at all costs. It is because of our concern to spare Portuguese blood that we are appealing for a civic spirit.
"All medical personnel, especially those in hospitals, should hold themselves ready to give help, though it is hoped this will not be needed. To all political and military forces, the Command advises maximum caution to avoid any action which may be dangerous. It is not our intention to shed blood unnecessarily, but if we meet provocation we shall deal with it.
"Go back to your quarters, and wait for orders which will be given by the Movement of the Armed Forces. Commanders will be held responsible for any attempt, in any form whatsoever, to lead their sub-ordinates into conflict with the Armed Forces.
"We appeal to the forces of the GNR (National Guard) and PSP (Riot Police) - and even to the DGS (Political Police) and Portuguese Legion - who may have been recruited under false pretences to remember their civic duty of maintaining public order. In the present situation this can only be achieved if there is no reaction against the Armed Forces Attention, all military and police units.
"Since the Armed Forces have decided to take your place in the present situation any opposition to the troops which surround the city will be dealt with drastically. By not obeying this advice you could provoke a senseless blood-bath, whose responsibility will be yours alone."
Here is the original TV announcement: https://www.facebook.com/1073423219/videos/10202550689303145/?t=24