PIDE

The Polícia Internacional e de Defesa do Estado or PIDE (International and State Defence Police), was the main tool of repression used by the authoritarian regime of António de Oliveira Salazar in Portugal during the Estado Novo.

Although the name PIDE was only used from 1945 to 1969, the whole network of secret police forces which existed during the 40 years of the regime are commonly known as PIDE.

PVDE
The origins of PIDE can be traced to 1933, the year of the inauguration of the Estado Novo. Under direct orders from Salazar himself, the PVDE (Polícia de Vigilância e de Defesa do Estado; "State Defence and Surveillance Police") was created, with two main sections:
 * Social and Political Defence section, which was used to prevent and repress crimes of a political and social nature (see: Censorship)
 * International Section, which was used to control the entrance of immigrants, to expel undesirable immigrants and to take care of counter-espionage and/or international espionage

In 1936, the prison of Tarrafal was created in the Portuguese colony of Cape Verde. This camp, under the direct control of the PVDE, was the destination for those political prisoners considered dangerous by the regime. Throughout the more than 40 years of the Estado Novo, 32 people lost their lives in Tarrafal, which was known for its severe methods of torture.

Also in 1936, with the beginning of the Spanish Civil War and in 1937 with the attempt against Salazar's life by anarchist militants, the PVDE started focusing its battle against communism and the underground Portuguese Communist Party. During this pre-World War II period, several Italian and German advisors came to Portugal to help the PVDE to adopt a model similar to the Gestapo.

During World War II, the PVDE experienced its most intense period of activity. Neutral Lisbon was the European centre of espionage and one of the favourite exile destinations. Writers such as Ian Fleming (the creator of James Bond) were based there, while other prominent people such as the Duke of Windsor and the Spanish Royal Family were exiled in Estoril. German spies attempted to buy information on trans-Atlantic shipping to help their submarines fight the Battle of the Atlantic. The Spaniard Juan Pujol Garcia, better known as Codename Garbo, passed on misinformation to the Germans, hoping it would hasten the end of the Franco regime - he was recruited by Britain as a double agent while in Lisbon. Conversely, William Colepaugh, an American traitor, was recruited as an agent by the Germans while his ship was in port in Lisbon - he was subsequently landed by U-boat U-1230 in Maine before being captured. In June 1943, a commercial airliner carrying the actor Leslie Howard was shot down over the Bay of Biscay by the Luftwaffe after taking off from Lisbon, possibly because German spies in Lisbon believed that Prime Minister Winston Churchill was on board.

Several American reports called Lisbon "The Capital of Espionage". However, the PVDE always maintained a neutral stance towards foreign espionage activity, as long as no one intervened in Portuguese internal policies.

PIDE
In 1945, the PVDE was dissolved and replaced by the PIDE. Unlike its predecessor, which sought inspiration in the Gestapo, PIDE followed the Scotland Yard model. As a section of the Polícia Judiciária (Investigation Police), it had full powers to investigate, detain and arrest anyone who was thought to be plotting against the State. It had two main functions: PIDE is considered by many authors as being one of the most functional and effective secret services in history. Using a wide network of covert cells, which were spread throughout Portugal and its overseas territories, PIDE had infiltrated agents into almost every underground movement, including the Portuguese Communist Party as well as the independence movements in Angola and Mozambique. The PIDE encouraged citizens - the so-called bufos (snitches) - to denounce suspicious activities, through the use of monetary and prestige incentives. This resulted in an extremely effective espionage service which was able to fully control almost every aspect of Portuguese daily life. Thousands of Portuguese were arrested and tortured in PIDE's prisons.
 * Administrative functions (which included those related to the migration services)
 * Criminal prevention and repression functions

The PIDE intensified its actions during the Portuguese Colonial War, creating a successful paramilitary unit called Flechas (Arrows). Yves Guérin-Sérac, a former officer of the French Army and founder of the OAS right-wing terrorist group during the Algerian War of Independence (1954–62), set up "Aginter Press" in Lisbon and participated with the PIDE in covert operations.

DGS
In 1969, Marcello Caetano changed the name PIDE to DGS (Direcção Geral de Segurança, "General Security Directorate"). The death of Salazar and the subsequent ascension of Caetano brought some attempts at democratization, in order to avoid popular insurgency against censorship, the ongoing colonial war and the general restriction of civil rights. This resulted in a decrease in the perceived level of violence used by the secret police and a consequent reduction in its effectiveness.

End of PIDE/DGS
The most dramatic moments of the 1974 Carnation Revolution occurred near the PIDE/DGS headquarters, in the infamous António Maria Cardoso Street. Unidentified agents, desperate after being surrounded by rebellious troops and a throng of citizens, opened fire from the top of the building, killing four demonstrators. These were the only victims of the coup d'état which brought down the dictatorship.

This was the last strategic point to be occupied by the insurgents, thus leading to the escape of the agents and the destruction of most of the records. In the days following the revolution, most escaped to Spain or went underground. Some of the archives were reportedly handed over by the Portuguese Communist Party to Soviet agents.

After being sanitized, the corporation continued its operations in the Portuguese colonies under the name of the Military Information Police (Polícia de Informação Militar).

A commission was created for the extinction of the secret police. The remainder of the documents since 1990 are in the Torre do Tombo National Archive. They can be consulted, but the names of agents and informers are not disclosed.

The only PIDE agents who faced trial were those responsible for the death of exiled opposition leader Humberto Delgado. They were tried in absentia and the case dragged on for several years. None of them ever served time in jail.

Because of the memory of the abuses of the PIDE/DGS in supporting the regime the establishment of a new civilian intelligence agency was delayed for more than a decade. However, following a terrorist attack on the Embassy of Turkey, the assassination of a Palestine Liberation Organization representative at a Socialist International conference in 1983, and a number of domestic terrorist attacks by isolated far-left and far-right groups, the Portuguese government became convinced of the need for a new intelligence agency. This led to the establishment of the Sistema de Informações da República Portuguesa (SIRP, Intelligence System of the Portuguese Republic) in 1984.