Following the January 1966 coup — in which most of the senior officers killed were from the North and the West, and most of the coup-plotters were Igbo — and the July 1966 counter-coup that elevated Yakubu Gowon, sustained violence against Igbo civilians and other Easterners broke out in northern cities. The killings of September and October 1966 in Kano, Kaduna, Jos, Zaria, Bukuru and elsewhere were the most severe, with attacks on Igbo neighbourhoods, markets, the Sabon Gari ("stranger") quarters, and on Igbo soldiers within barracks. Estimates of those killed range from approximately 8,000 to more than 30,000, with widely cited figures clustering around 30,000; up to two million Easterners fled back to the Eastern Region in what historians consistently describe as one of the most severe episodes of ethnic violence in Nigerian post-independence history. The pogroms made the secession that Ojukwu would declare on 30 May 1967 effectively inevitable in the eyes of the Eastern leadership.
Figure 1
Anti-Igbo pogroms in the North, 1966 — killed and displaced (mid-range estimates)
Roughly nine thousand killed and 1.8 million displaced in three waves. The September-October peak — Kano, Kaduna, Jos, Zaria — is what made the federation unsalvageable.