On Oct. 1, 1960, Nigeria gained independence, becoming a member of the Commonwealth of Nations and joining the United Nations. Organized as a loose federation of self-governing states, the independent nation faced the overwhelming task of unifying a country with 250 ethnic and linguistic groups.

Rioting broke out in 1966, and military leaders, primarily of Ibo ethnicity, seized control. In July, a second military coup put Col. Yakubu Gowon in power, a choice unacceptable to the Ibos. Also in that year, the Muslim Hausas in the north massacred the predominantly Christian Ibos in the east, many of whom had been driven from the north. Thousands of Ibos took refuge in the eastern region, which declared its independence as the Republic of Biafra on May 30, 1967. Civil war broke out. In Jan. 1970, after 31 months of civil war, Biafra surrendered to the federal government.