Before Emeka Ojukwu declared the Republic of Biafra in May 1967, Isaac Adaka Boro had declared the Niger Delta Republic in February 1966. Boro formed the Niger Delta Volunteer Force, an armed militia whose members mainly comprised the Ijaw ethnic group, and declared the Republic of the Niger Delta on 23 February 1966 and fought against Nigerian federal forces for 12 days, but was eventually defeated and then imprisoned.