From: There Was A Country: A Personal History of Biafra, by Chinua Achebe (Penguin, 2012), Kindle Loc. 1307-1326:
Looking back, the naively idealistic coup of January 15, 1966, proved a terrible disaster. It was interpreted with plausibility as a plot by the ambitious Igbo of the East to take control of Nigeria from the Hausa/Fulani North. Six months later, I watched horrified as Northern officers carried out a revenge coup in which they killed Igbo officers and men in large numbers. If it had ended there, the matter might have been seen as a very tragic interlude in nation building, a horrendous tit for tat. But the Northerners turned on Igbo civilians living in the North and unleashed waves of brutal massacres that Colin Legum of The Observer (UK) was the first to describe as a pogrom. Thirty thousand civilian men, women, and children were slaughtered, hundreds of thousands were wounded, maimed, and violated, their homes and property looted and burned—and no one asked any questions. A Sierra Leonean living in Northern Nigeria at the time wrote home in horror: “The killing of the Igbos has become a state industry in Nigeria.”
What terrified me about the massacres in Nigeria was this: If it was only a question of rioting in the streets and so on, that would be bad enough, but it could be explained. It happens everywhere in the world. But in this particular case a detailed plan for mass killing was implemented by the government—the army, the police—the very people who were there to protect life and property. Not a single person has been punished for these crimes. It was not just human nature, a case of somebody hating his neighbor and chopping off his head. It was something far more devastating, because it was a premeditated plan that involved careful coordination, awaiting only the right spark.
Throughout the country at this time, but particularly in Igbo intellectual circles, there was much discussion of the difficulties of coexisting in a nation with such disparate peoples and religious and cultural backgrounds. As early as October 1966, some were calling for outright war. Most of us, however, were still hoping for a peaceful solution. Many talked of a confederation, though few knew how it would look.
In the meantime, the Eastern Region was tackling the herculean task of resettling the refugees who were pouring into the East in the hundreds of thousands. It was said at the time that the number of displaced Nigerian citizens fleeing from other parts of the nation back to Eastern Nigeria was close to a million.