The Nigerian Eastern Region declares independence as the Republic of Biafra, sparking a civil war.

The Nigerian Civil War (6 July 1967 15 January 1970; also known as the Nigerian-Biafran War or the Biafran War) was a civil war fought between the government of Nigeria and the Republic of Biafra, a secessionist state which had declared its independence from Nigeria in 1967. Nigeria was led by General Yakubu Gowon, while Biafra was led by Lt. Colonel Odumegwu Ojukwu. Biafra represented the nationalist aspirations of the Igbo ethnic group, whose leadership felt they could no longer coexist with the federal government dominated by the interests of the Muslim Hausa-Fulanis of northern Nigeria. The conflict resulted from political, nomic, ethnic, cultural and religious tensions which preceded Britain's formal decolonization of Nigeria from 1960 to 1963. Immediate causes of the war in 1966 included ethno-religious violence and anti-Igbo pogroms in Northern Nigeria, a military coup, a counter-coup and persecution of Igbo living in Northern Nigeria. Control over the lucrative oil production in the Niger Delta also played a vital strategic role.Within a year, the Federal Government troops surrounded Biafra, captured coastal oil facilities and the city of Port Harcourt. A blockade was imposed as a deliberate policy during the ensuing stalemate which led to mass starvation. During the two and half years of the war, there were about 100,000 overall military casualties, while between 500,000 and 2 million Biafran civilians died of starvation.In mid-1968, images of malnourished and starving Biafran children saturated the mass media of Western countries. The plight of the starving Biafrans became a cause clbre in foreign countries, enabling a significant rise in the funding and prominence of international non-governmental organizations (NGOs). The United Kingdom and the Soviet Union were the main supporters of the Nigerian government, while France, Israel (after 1968) and some other countries supported Biafra. The United States' official position was one of neutrality, considering Nigeria as 'a responsibility of Britain', but some interpret the refusal to recognize Biafra as favouring the Nigerian government.

Nigeria ( ), officially the Federal Republic of Nigeria, is a country in West Africa. It is the most populous country in Africa. It is geographically situated between the Sahel to the north and the Gulf of Guinea to the south in the Atlantic Ocean. It covers an area of 923,769 square kilometres (356,669 sq mi), with a population of over 211 million. Nigeria borders Niger in the north, Chad in the northeast, Cameroon in the east, and Benin in the west. Nigeria is a federal republic comprising 36 states and the Federal Capital Territory, where the capital, Abuja, is located. The largest city in Nigeria is Lagos, one of the largest metropolitan areas in the world and the second-largest in Africa.

Nigeria has been home to several indigenous pre-colonial states and kingdoms since the second millennium BC, with the Nok civilization in the 15th century BC marking the first internal unification in the country. The modern state originated with British colonialization in the 19th century, taking its present territorial shape with the merging of the Southern Nigeria Protectorate and Northern Nigeria Protectorate in 1914 by Lord Lugard. The British set up administrative and legal structures while practising indirect rule through traditional chiefdoms in the Nigeria region. Nigeria became a formally independent federation on October 1, 1960. It experienced a civil war from 1967 to 1970, followed by a succession of democratically elected civilian governments and military dictatorships, until achieving a stable democracy in the 1999 presidential election; the 2015 election was the first time an incumbent president had lost re-election.Nigeria is a multinational state inhabited by more than 250 ethnic groups speaking 500 distinct languages, all identifying with a wide variety of cultures. The three largest ethnic groups are the Hausa in the north, Yoruba in the west, and Igbo in the east, together comprising over 60% of the total population. The official language is English, chosen to facilitate linguistic unity at the national level. Nigeria's constitution ensures freedom of religion and it is home to some of the world's largest Muslim and Christian populations, simultaneously. Nigeria is divided roughly in half between Muslims, who live mostly in the north, and Christians, who live mostly in the south; indigenous religions, such as those native to the Igbo and Yoruba ethnicities, are in the minority.Nigeria is a regional power in Africa, a middle power in international affairs, and is an emerging global power. Nigeria's economy is the largest in Africa, the 25th-largest in the world by nominal GDP, and 25th-largest by PPP. Nigeria is often referred to as the Giant of Africa owing to its large population and economy and is considered to be an emerging market by the World Bank. However, the country ranks very low in the Human Development Index and remains one of the most corrupt nations in the world. Nigeria is a founding member of the African Union and a member of many international organizations, including the United Nations, the Commonwealth of Nations, NAM, the Economic Community of West African States, and OPEC. It is also a member of the informal MINT group of countries and is one of the Next Eleven economies.