On April 21, 1967 a group of middle-ranking right-wing Greek army officers, the Colonels, seized power in Athens weeks before scheduled elections, overthrowing the caretaker government and installing a military dictatorship that ruled Greece for seven years. Led by Colonels George Papadopoulos and Nikolaos Makarezos and Brigadier Stylianos Pattakos, the plotters used the NATO contingency plan codenamed Prometheus to move tanks into Athens before dawn, seizing parliament, ministries, the broadcaster, and communications, and arresting leading politicians, including acting Prime Minister Panagiotis Kanellopoulos, who were held incommunicado. The coup preempted a feared victory by Georgios Papandreou's Centre Union in the May 28 elections and a rumored Generals' coup.
At 6 a.m. Papadopoulos announced the suspension of eleven articles of the constitution, allowing arrest without warrant; thousands on a prepared list of some 10,000 names were rounded up, and prominent figures like the composer Mikis Theodorakis were detained.
King Constantine II, though remaining head of state, was coerced into swearing in the junta and later fled after a failed December 1967 counter-coup. The regime fell in July 1974.
Films & Footage
Georgios Papadopoulos, leader of the Colonels' regime, press photo, 1967. Photo: David Mazzarella / Associated Press
Independent research, added record by record. Hover any label for what it means.
Target identified in Coup Atlas research: The caretaker government of acting Prime Minister Panagiotis Kanellopoulos, arrested and held incommunicado in the early hours of April 21, 1967; Kanellopoulos was not physically harmed. King Constantine II remained nominal head of state but was coerced into legitimizing the junta.
RESEARCHED NAME
Key figures
Panagiotis Kanellopoulos (acting prime minister, arrested)
George Papadopoulos (colonel, coup strongman and later ruler)
Stylianos Pattakos and Nikolaos Makarezos (co-leaders of the coup)
King Constantine II (head of state coerced into swearing in the junta)
Sources
On 21 April 1967, just weeks before scheduled elections, a group of right-wing army officers led by Brigadier Stylianos Pattakos and Colonels George Papadopoulos and Nikolaos Makarezos seized power in a coup, using surprise and confusion; by the early morning hours the whole of Greece was in the hands of the colonels, all leading politicians including acting Prime Minister Panagiotis Kanellopoulos had been arrested and held incommunicado, and at 6:00 a.m. Papadopoulos announced that eleven articles of the constitution were suspended.
The conspirators launched their coup from the Armored Training Centre; tanks moved out at 2:00 a.m. and seized key government sites including Parliament, ministries, the national broadcaster, the telecommunications authority, and the royal palace, while Colonel Ioannis Ladas mobilized units to arrest senior figures, and the plotters activated NATO's anti-communist contingency plan Prometheus under the pretense of preventing a leftist uprising though no such threat was imminent.
SOURCE REVIEWEDNeos Kosmos, April 21 1967: The coup that shattered Democracy in Greeceopen source ↗
On the morning of April 21, 1967 coup leaders, mostly colonels not generals, drove armored vehicles into Athens, arrested the leading politicians, and pressured King Constantine II to acknowledge their deed; later in the day Constantine issued a decree suspending the civil liberty provisions of the constitution, and Colonel George Papadopoulos emerged as the chief leader, with the coup preempting an expected Centre Union election victory.
SOURCE REVIEWEDEBSCO Research Starters, Greek Coup Leads to Military Dictatorshipopen source ↗
An account records that King Constantine, refusing to legitimise the coup at first, told the colonels they were oath-breakers leading the country into peril, but, isolated and with no loyal military forces on which to rely, he reluctantly agreed to swear in the junta on the condition it be made up largely of civilian ministers, and that it was the government sworn in during the early evening of April 21 that formalised the coup.
SOURCE REVIEWEDEuropean Royal History, December 13 1967 Counter Coup in Greeceopen source ↗
Editorial Note
Head-of-state nuance: the government deposed on April 21 was the caretaker cabinet of acting PM Kanellopoulos; King Constantine II remained the nominal head of state but was coerced into swearing in the junta, and his own attempted counter-coup came on 13 December 1967 and failed, driving him into exile. The dataset's not physically harmed fate applies to the deposed leadership, which was arrested but not physically harmed. The mass arrests (a prepared list of roughly 10,000 names, detentions of figures like Mikis Theodorakis, and later torture of political prisoners) are recorded as documented consequences. Arc note: the junta ruled until 24 July 1974, when it fell over the Cyprus crisis and the Turkish invasion; a hardliner counter-coup by Ioannidis in November 1973 is a separate later event.
How It Unfolded
Hand-coded by Coup Atlas from the sources on this page, using a fixed list of tactics. Only events we have read through carry this coding, so most records do not have it yet.
Led by
Military
How long it took
Under a day — resolved within 24 hours
Troop movements in the capital or key cities
Mass arrests of officials, officers, or opponents
Declaration of martial law or curfew
Seizure of broadcasters / coup declaration on state media
Cross-Reference
Datasets agree. At least two of the three reference datasets we check against carry this event, and none of them disagrees about its date or its result.
Identifiers for finding this same event in the other datasets:
Coup Atlas research identifies the target as: The caretaker government of acting Prime Minister Panagiotis Kanellopoulos, arrested and held incommunicado in the early hours of April 21, 1967; Kanellopoulos was not physically harmed. King Constantine II remained nominal head of state but was coerced into legitimizing the junta..
Baseline coding: Incumbent executive removed from power. Recorded leader fate: deposed; 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
“Army in Greece installs Premier after Take-over,” April 22, 1967
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 →
