Military intervention occurred when the army seized the power on 12 September 1980 through the chain of order and command. The National Security Council (MGK), which was composed of Kenan Evren, the Chief of the General Staff, and the Force Commanders, dissolved the Parliament and the Government.

Martial law was declared all over the country. The chairmen of the AP, CHP, MHP and MSP were taken into custody. The MGK which vested itself with the legislative and executive powers, appointed Kenan Evren, the Chairman of the Council, as the Head of State. A new government was formed by Admiral Bulend Ulusu.

Turgut ozal, the Undersecretary of the Prime Ministry of the final AP government and the architect of the 24 January decisions, was appointed as the Deputy Prime Minister Responsible for the Economy. The economic stability policies which had been started by the Demirel government were continued in this period.

The most significant development in foreign policy was the approval by the MGK of "the Rogers Plan", named after the NATO Supreme Commander, permitting Greece to return to the military wing of NATO, that was contrary to the policy that had been followed by Turkey for a long period of time. It was decided in June 1981 to form a new "Constituent Assembly" which would include the MGK members and the Advisory Assembly (DM) to prepare a new constitution.

On the day that the members of the Advisory Assembly were announced, all the political parties which had earlier been banned, were closed by the MGK and their properties were confiscated. The new constitution prepared by the Constitutional Commission of the DM was submitted to a public referendum on 7 November 1982 and was approved by a majority vote of 91.2 percent. After the approval of the new Constitution, Kenan Evren acquired the title of "President". The Political Parties Law went into effect on 24 April 1983 and the political activities were gradually permitted for the establishment of new political parties.

At the central right wing, the Nationalist Democracy Party (MDP), led by Ret. General Turgut Sunalp was established. The MDP defined itself as the continuation of the spirit and philosophy of 12 September. The second initiative, which was not quite welcomed by the MGK, came from Turgut ozal who had resigned from the Ulusu government in 1982. He established the Motherland Party (ANAP) which promised to make economic reforms, liberalize the economy and implement free market policies.

The third was the Populist Party (HP), which was aimed to be a left of center party. Its chairman was Necdet Calp, a former Undersecretary of the Prime Ministry in the Bulend Ulusu government. Along with these parties, the True Path Party (DYP), which was known to be a continuation of the AP, and the Social Democracy Party (SODEP), led by Erdal Inonu, the son of Ismet Inonu, were established. However, the MGK investigated the founding members of the new parties and vetoed a significant number of them.

The lists of the SODEP and DYP were vetoed the most. In fact, they were practically vetoed out of the general election so that only ANAP, MDP and HP could participate in the elections on 6 November 1983. Turgut ozal's ANAP won the election getting 45.1 percent of the votes and 53 percent of the seats in the Parliament. The function of the MGK ended and the four members of the MGK became members of the Presidential Council when the Turkish Grand National Assembly (TGNA) convened on 24 November 1983. The first ANAP Government was formed on 13 December 1983 under the chairmanship of Turgut ozal.