The Counter-Coup of July 1966

In July 1966 northern officers and army units staged a counter-coup against the government of Major General Johnson Aguiyi-Ironsi, in which Ironsi and a number of other Igbo officers were killed. According to the Library of Congress country study, many northerners feared that Ironsi intended to deprive them of power and to build an Igbo-dominated centralised state; his decree abolishing the federal structure had been seen as disregarding the strength of regional and ethnic feeling. The country study elsewhere describes the coup of 29 July 1975 as falling on the ninth anniversary of the revolt that had brought Yakubu Gowon to power.

Lieutenant Colonel Yakubu Gowon became head of state. His first act was to repeal Ironsi's decree and restore the federal system, and he released Obafemi Awolowo and Anthony Enahoro from prison.

After the January coup, Ironsi's government suspended the constitution and moved towards a unitary state, which Ironsi and his advisers believed would end the regionalism that had blocked political progress. According to the Library of Congress country study, Ironsi's decree showed a dangerous disregard for regional feeling after the bloody coup, and he was open to accusations of favouring the Igbo. Some northern leaders spoke seriously of secession, and many northerners feared that he meant to deprive them of power. The January coup itself had been carried out mainly by Igbo officers and had killed the premiers of the north and west, Ahmadu Bello and Samuel Akintola, together with senior officers of northern origin (country study). Wikipedia's article on Murtala Muhammed records that he led the mutiny of the night of 29 July 1966 in Abeokuta.

Violence against Igbo in the north followed, and many fled to the Eastern Region. The crisis led to the Eastern Region's secession as Biafra in May 1967 and to civil war (country study).