See History Of Nigeria Government Below….
A former British colony, Nigeria became independent on September 30, 1960 and a Republic on October 1, 1963. The first independent government was formed by a coalition of northern and eastern political parties, with Nnamdi Azikiwe as the president and Abubakar Tafawa Balewa as prime minister.
Political tension led to disturbances in parts of the country, particularly the Western Region, and in January 1966 the Nigerian armed forces seized power.
The new federal military government, headed by Major-General Aguiyi Ironsi suspended the constitution of the republic. In May 1966 Ironsi was assassinated in a second military coup and was succeeded by Lt. Col. Yakubu Gowon who restored the federal system and reorganized the four existing regions into twelve states.
General Gowon remained in power until July 1975 when he was overthrown in a coup led by Brigadier Murtala Mohammed. Murtala Mohammed reversed some of General Gowon’s unpopular policies, set a date for the return to civilian rule and increased the number of states from twelve to nineteen. In February 1976 Mohammed was assassinated in a coup attempt, and his deputy General Olusegun Obasanjo replaced him, continuing many of his policies and taking responsibility for the final stages of Nigeria’s return to civilian rule.
In 1978 a constitution was introduced, which moved Nigeria away from the Westminister parliamentary model to a presidential system with a clear separation of powers and with an executive governor in each state. The twelve year ban on political parties was lifted and five parties (NPN, NPP, UPN, PRP, GNPP) eventually emerged to contest the elections in July/August 1979.
Alhaji Shehu Shagari of the National Party of Nigeria (NPN) emerged the winner of the presidential election and he was sworn in as the country’s first executive president on October 1, 1979. At the next elections, in 1983, amid widespread allegations of rigging and intimidation NPN was returned to power and Shehu Shagari was sworn in for a second term.
On 31 December 1983 the armed forces, led by Major-General Muhammadu Buhari, intervened again. The Supreme Military Council (SMC) suspended the constitution, banned political parties and arrested politicians. The coup was welcomed initially, but popular opposition grew as dissatisfaction grew over the operation of special tribunals set up to try former politicians, and at powers of detention without trial and press censorship.
In August 1985 military officers led by Major-General Ibrahim Babangida overthrew the government of Buhari. Several decrees were revoked, while journalists and other detainees were released.