He is known for being the brief Military Administrator of the Mid-Western State of Nigeria during the Mid-West invasion in the early phase of the civil war.

[3] Okonkwo was a military doctor and the commanding officer of the Nigerian Armed Forces Medical Service in Benin City right before the Civil War.

On 9 August 1967, a force of 3,000 Biafran troops crossed the Niger bridge, with one group making a dash for Benin City.

On 14 August the Biafran command in Enugu announced that Major Okonkwo had been appointed Military Administrator of the Mid-Western Region.

[4] In his broadcast declaring the independent Republic of Benin, Okonkwo belatedly tried to rally non-Igbo groups.