First Republic & Civil War — the Asaba Massacre (1960–1970) — Delta State

9 August 1963 — Mid-West plebiscite — peaceful, but exposes deep Edo–Urhobo–Itsekiri–Ijaw–Anioma cleavages that prefigure later state-creation fights.
The Mid-West Invasion (9–20 Aug 1967) — Biafran Brig. Victor Banjo crosses the Niger at Onitsha-Asaba bridge with the 101 Division; declares the short-lived Republic of Benin (Sept 1967); federal 2 Division under Col. Murtala Muhammed retakes Benin and pushes east.
★ Asaba Massacre, 5–7 October 1967 — as the 2 Division crosses the Niger after a costly engagement at Onitsha, federal troops under Major Ibrahim Taiwo order Asaba's men to assemble at Ogbe-Osowa Square in a "welcome dance" wearing the *akwa-ocha* white cloth. Between 700 and 1,000 Anioma men and boys are machine-gunned; surviving women are systematically raped over the following weeks. The massacre is suppressed in federal accounts for forty years; documented from 2010 by S. Elizabeth Bird & Fraser Ottanelli (University of South Florida). Pattern: state mass-atrocity. See Asaba Massacre.
Onitsha Bridge battles (Mar–Oct 1967, May 1968) — the longest contested crossing of the war; Biafran 11 Brigade defends Onitsha-Asaba bridge; federal 2 Division loses thousands in repeated assaults.
Ogwashi-Uku, Ibusa, Issele-Uku reprisals (1968) — federal punitive killings continue through Anioma towns.
Naval bombardment of Forcados and Escravos (1968) — Shell tank-farm at Forcados shelled by NN *Nigeria*; oil exports suspended.