LAGOS, Nigeria — Fifty years ago, on Jan. 15, Nigeria’s civil war ended. Fought between the country’s southeast region, which seceded and called itself Biafra, and the rest of the country, which Britain supported and armed, the war was brutal. Over a million people died during three years of conflict. After being starved into submission by a blockade, the Biafrans surrendered and their leaders promised to be “loyal Nigerian citizens.”

Half a century later, the war’s legacy continues to hold Nigeria captive. It simultaneously brings the country together and pushes it apart.

In the early aftermath of the war, the country appeared to be unified. Despite the war’s shocking human tragedy, reconciliation was remarkably rapid. War and partition ironically created a consensus: The country, now united, should never be allowed to break apart again. The government declared a general amnesty for wartime combatants, refused to punish either those who led the secession or those who suppressed it and did not give medals to any soldiers who fought in the so-called Brothers’ War.

The country was re-engineered to prevent another secession. To find a way for Nigeria’s more than 250 ethnic groups to live together peacefully, the country was split into 36 states, most of which coincided with the location of a major ethnic group. The federal government, whose power was increased, provided the states with funds — which created a financial deterrent against secession.