See also: 1965 in Nigeria, 1967 in Nigeria and Timeline of Nigerian history.

Events

January

• January 15, 1966 The first of many Military Coups in Nigeria deposes the Nigerian First Republic; Prime Minister Tafawa Balewa, was assassinated along with the premier of Northern Nigeria, Ahmadu Bello, and the Finance Minister, Festus Okotie-Eboh
• January 16, 1966 The Federal Military Government is formed, with General Johnson Aguiyi-Ironsi as the Head of State and Supreme Commander of the Federal Republic.

June

• July 29, 1966 A counter-coup by military officers of northern extraction, deposes the Federal Military Government; General Johnson Aguiyi-Ironsi is assassinated along with Adekunle Fajuyi, Military Governor of Western Region. General Yakubu Gowon becomes Head of State.