Following the military coup that killed Nigeria's first prime minister, Alhaji Sir Abubakar Tafawa Balewa, and the premiers of the northern and western regions, chaos spread throughout the country, with no central government and suddenly diminished regional leadership. In an attempt to restore normalcy, Major General Johnson Thomas Umunnakwe Aguiyi Ironsi gained control of the military regime, pledging to quickly return Nigeria to democratic rule.

Ironsi attempted to bring renewed discipline to the army, passed laws allowing for greater press freedoms, and on May 24, 1966, announced plans for a centralized Nigerian constitution. He suspended regional constitutions, dissolved all legislative bodies, banned political parties, and formed a single Federal Military Government.

According to Charles Hauss, the announcement caused widespread concern that the coup that killed Balewa was orchestrated by Ironsi to bring his tribe, the Igbo, to power. In the largely Muslim north, leaders and the population reacted angrily, accusing Ironsi of attempting to undercut Islamic representation in the sprawling nation. Fighting ensued between northerners and the Igbo, in which hundreds were killed. The violence culminated in July 1966, when northerners staged a second military coup in less than a year, killing Ironsi and many other Igbo leaders.