Following the defeat in the Cross River region, the Biafrans regrouped the remnants of their troops and created the Biafran 12th Division under the command of Lt. Col. Festus Akagha. The 12th Division was divided into the 56th Brigade stationed in Arochukwu and the 58th Brigade stationed in Uyo.
On March 8, 1968, the beaches at Oron came under heavy Nigerian aerial and naval bombardment. The Nigerian 33rd Brigade under Col. Ted Hamman overran Biafran defensive positions and continued towards Uyo. Due to the swiftness of the Nigerian advance, Biafran officers began to lose control of their troops.
Consequently, hundreds of Biafran troops were cut off and forced to surrender after Nigerian troops stationed at Oron linked up with the Nigerian 16th and 17th Brigade in Uyo. The 16th Brigade under Col. E.A. Etuk and 17th Brigade under Lt. Col. Philemon Shande stormed through Eket and occupied Opobo.
With the Biafrans in retreat, the Nigerian 15th Brigade under Col. Ipoola Alani Akinrinade stationed at Bonny launched an attack on Port Harcourt. At the time, Port Harcourt was defended by the Biafran 52nd Brigade under Col. Ogbugo Kalu. After heavy fighting, Nigerian troops captured and dug in at Onne; their success would be short lived.
A division of Biafran soldiers under an Italian-born Biafran mercenary unexpectedly counter-attacked, inflicting heavy casualties before forcing the Nigerians to retreat from Onne. The Biafran 14th Battalion stationed in Bori panicked and retreated from the town after spotting Nigerian soldiers wearing the insignia of the Nigerian 14th Brigade. As Biafran
lines around Port Harcourt crumbled, a message was sent over Radio Biafra for the defense of the city.
On May 19 the Biafran Maj. Joseph Achuzie arrived in Port Harcourt and was made commander of Biafran troops defending the city. Port Harcourt was subjected to heavy Nigerian artillery bombardment while defending Biafran troops fiercely resisted. During five days of heavy fighting, Port Harcourt’s airport and army barracks changed hands on numerous occasions but by May 24 most Biafran troops had been pushed out of the city into the surrounding areas.
Maj. Achuzie stubbornly continued to fight against the Nigerians before narrowly escaping death after almost being run over by an armored car; it was then that Maj. Achuzie abandoned fighting and retreated to Igwuruta. The liberation
of Port Harcourt completely denied Biafra access to the sea. Nigerian authorities regarded it as a significant victory.