The coup was staged by a group of 38 young Turkish military officers, acting outside the Staff Chiefs' chain of command.
It was orchestrated by Alparslan Türkeş and ultimately led on May 27, 1960, by General Cemal Gürsel, against the democratically elected government of the Democrat Party. Alparslan Türkeş was a member of the junta (National Unity Committee).
The incident took place at a time of both socio-political turmoil and economic hardship, as US aid from the Truman doctrine and the Marshall Plan was running out and so Prime Minister Adnan Menderes planned to visit Moscow in the hope of establishing alternative lines of credit.
Colonel Alparslan Türkeş orchestrated the plot. He was a member of the junta (National Unity Committee) and had been among the first 16 officers trained by the United States in 1948 to form a stay-behind counter-guerrilla. As such, he explicitly stated his anti-communism and his faith and allegiance to NATO and CENTO in his short address to the nation, but he remained vague on the reasons of the coup. On the morning of May 27, Türkeş declared the coup over the radio, which ultimately announced “the end of one period in Turkish history and usher in a new one”:
The Great Turkish Nation: Starting at 3:00 am on the 27th of May, the Turkish armed forces have taken over administration throughout the entire country. This operation, thanks to the close cooperation of all our citizens and security forces, has succeeded without loss of life. Until further notice, a curfew has been imposed, exempt only to members of the armed forces. We request our citizens to facilitate the duty of our armed forces and assist in reestablishing the nationally desired democratic regime.
In a press conference on the following day, Cemal Gürsel emphasized that the “purpose and the aim of the coup are to bring the country with all speed to a fair, clean and solid democracy... I want to transfer power and the administration of the nation to the free choice of the people”.
The junta forced 235 generals and more than 3,000 other commissioned officers into retirement; purged more than 500 judges and public prosecutors and 1400 university faculty members and put the chief of the General Staff, the president, the prime minister, and other members of the administration under arrest. It followed by the appointment of the commander of the army General Cemal Gürsel, as the provisional head of state, prime minister, and the minister of defense.
The minister of the interior, Namık Gedik, committed suicide while he was detained in the Turkish Military Academy. President Celal Bayar, prime minister Adnan Menderes and several other members of the administration were put on trial before a court-appointed by the junta on the island Yassıada in the Sea of Marmara. The politicians were charged with high treason, misuse of public funds, and abrogation of the constitution.
The tribunals ended with the execution of Adnan Menderes, Minister of Foreign Affairs Fatin Rüştü Zorlu, and Minister of Finance Hasan Polatkan on İmralı island on 16 September 1961.