Coup Atlas Research Database
← Back to explorer
23509281974AttemptedPalace coup

Portugal, 1974 — palace coup attempt

Portugal (PRT)Southern Europe, EuropeSeptember 28, 1974

Event Summary

The dataset records an event coded as an attempted palace coup in Portugal on 28 September 1974, corresponding to the failed bid by President Antonio de Spinola to reassert conservative control over the revolution that had toppled the dictatorship in April. Spinola, the general to whom Marcelo Caetano had surrendered power, had become president but grew alarmed at the leftward radicalization driven by the Armed Forces Movement and the Communist Party. To test the balance of power and create a pretext for seizing fuller authority, he called for a mass demonstration of the silent majority for 28 September 1974 to rally moderate and conservative Portuguese against the left.

But left-wing forces, communists, socialists, and radical soldiers, erected armed barricades across the country and blocked the roads into Lisbon, preventing Spinola's supporters from gathering. The demonstration was called off, right-wing figures were arrested, and Spinola, his position collapsing, resigned two days later on 30 September, deepening the leftward turn of the Portuguese revolution.

Researched Details

Researched

Independent research, added record by record. Hover any label for what it means.

Target identified in Coup Atlas research: President Spinola's silent majority bid failed and he resigned; the leftist revolution deepened
RESEARCHED NAME
Key figures
Antonio de Spinola (president of Portugal, coup instigator who failed)
Armed Forces Movement and Communist Party (leftist forces who blocked the bid)

Sources

Spinola called for a demonstration of the silent majority for 28 September 1974 to resist the political radicalization of the left, but it was frustrated by left-wing forces that erected barricades and prevented his supporters from reaching Lisbon.
SOURCE REVIEWED Portuguese American Museum, Carnation Revolution Antonio de Spinola open source ↗
Right on 27 to 28 September 1974 the right planned a coup, Spinola called for the silent majority demonstration, workers built barricades and blocked bridges, right-wingers were arrested, and Spinola resigned.
SOURCE REVIEWED Socialist Worker, Timeline of the Portuguese revolution open source ↗
Powerless after the failed demonstration, Spinola resigned on 30 September 1974 and was replaced by Costa Gomes.
SOURCE REVIEWED Portuguese American Museum, Carnation Revolution Antonio de Spinola open source ↗
After the failed September bid Spinola's support in the armed forces and among working class people was fast evaporating, and right-wing officers and civilians were arrested.
SOURCE REVIEWED Socialist Alternative, Revolution in Portugal 1974 open source ↗

Editorial Note

Date match to the 28 September 1974 silent majority crisis. Dataset codes it a palace coup with leader unharmed, reflecting Spinola's failed bid to seize fuller power; he resigned two days later. Well documented. Second of three Portugal records in this batch; Spinola would try again in March 1975.

Cross-Reference

Only one dataset carries it. One of the three reference datasets we check against carries this event; the others do not list it. That is not a contradiction — the datasets cover different periods and use different thresholds — but it means the record has had less outside corroboration.

Identifiers for finding this same event in the other datasets:

Cline Center id
23509281974

How the match is made is described in crossref-report.md.

Outcome and Target

Coup Atlas research identifies the target as: President Spinola's silent majority bid failed and he resigned; the leftist revolution deepened.

Baseline coding: Coup attempt failed to remove the incumbent. Recorded leader fate: remained in office; not physically harmed. The baseline file does not name individual targets; researched names are kept in a separate layer.

Baseline Dataset Citation

Cline Center Coup d’État Project Dataset, v2.2.2
Peyton, Buddy, Joseph Bajjalieh, Michael Martin, and Andrea Gerald. 2026. Cline Center Coup d’État Project Dataset. Cline Center for Advanced Social Research. V.2.2.2. February 17. University of Illinois Urbana-Champaign. doi: 10.13012/B2IDB-9651987_V10
⚑ This citation establishes the coded baseline record; use the claim-level sources above for the researched narrative.

Baseline Source-Document Entries

CSP

Named in the baseline source document; no article citation was recorded.

Luttwak

Named in the baseline source document; no article citation was recorded.

Wikipedia

New York Times

“LISBON RELEASES 2 SALAZAR AIDES Freeing of Prisoners Part of Shift to Right Since Leftist Coup Failed,” January 23, 1976

This is the citation trail carried by the baseline dataset, grouped by outlet and rejoined from the line-wrapped original. Coup Atlas has not independently re-checked every document; read the original before citing a specific claim. URLs the import damaged beyond safe repair are shown as plain text and listed in citations-report.md. How this list is built →

Know something about this event?
Tips are reviewed against sources before anything is added.