The causes of the Biafran/Nigeria Civil War stem from the 1 January 1914 forced British amalgamation of 250 diverse and distant ethic groups and two separate provinces into the single nation of Nigeria by combining the Northern Province protectorate, which provided a security buffer against the French and German colonies, and the Southern Province protectorate, which provided the raw materials for export and revenue. From the beginning of amalgamation (amalgamate: to mix or merge so as to combine, blend or unite), calls for secession from Nigeria went out from the Igbo ethnic group. The disparities arising from differences between British treatment of the two provinces was pointed out by Sir Hugh Clifford, Governor General of Nigeria, who stated that while Southern Province Nigerians were educated to the extent that skilled labor was readily available and many Nigerians had become professionals, like doctors and lawyers, there were no Northern Province Nigerians who had been "sufficiently educated to enable him to fill the most minor clerical post in the office of any government department" (James S. Coleman qtd. by The Daily Independent, "The 1914 amalgamation and how Britain underdeveloped Nigeria"). This illustrates the extent to which history, traditions, ethnological, racial, tribal, political, social, and religious barriers all hampered the creation of a unified state of Nigeria. At the advent of Nigerian independence on 1 October 1960, when Great Britain gave up colonial power over Nigeria forty-six years after amalgamation, three regions based on ethnic groupings were created to comprise the independent nation of Nigeria. The Hausa/Fulani were in the north; the Yoruba were in the west; the Igbo were in the south.

The Nigerian Civil War, between the self-declared secessionist nation of Biafra and the independent nation of Nigeria, began on 30 May 1967 and ended on 12 January 1970. Though there were complex multiple causes, the primary cause, as reflected in a statement made by the Igbo Eastern Military Governor, Lieutenant Colonel Chukumeka Odumegwu Ojukwu, was interethnic domination: "The brutal and planned annihilation of officers of Eastern Nigeria origin had cast serious doubt as to whether they could ever sincerely live together as members of a nation" (Ojiako qtd. by The Daily Independent). To compound the underlying ethnic hostilities, a controversial census in 1963, a disputed postindependence election in 1964, and explosive western regional elections in 1965 worsened hostilities, deepened secessionist agitations and triggered first military coup on 15 January 1966, led by Igbo (eastern region) Major Chukwuma "Kaduna" Nzeogwu. Though Nzeogwu's coup killed Nigerian Prime Minister Tafawa Balewa the Sarduana* of Sokoto, Sir Ahmadu Bello, no Eastern Igbos were killed, a fact that triggered the accusation that the coup was not political but rather ethnic and that the Igbos of the east were aiming for ethnic domination over north and south [*the Sarduana, a tribalist leader, opposed "emerging cosmopolitan, federal and democratic conscious" epitomized by the "new generation of Northerners" in favor of tribal traditions and structures (Okechukwu Jones Asuzu, The Politics of Being Nigerian)]. Later in 1966, a countercoup led by Igbo Major-General Johnson Umunakwe Aguiyi-Ironsi abolished the federal structure and introduced a unitary system of government in Nigeria: a unitary form has one central decision making power, with decisions communicated to and implemented by regional and local authorities (in comparison, the US is a federalist republic government while the UK is a unitary government). A "revenge coup" on 29 July 1966 resulted in the assassination of Major-General Aguiyi-Ironsi at Ibadan putting an end to his unitary government.

A summit of military leaders of the opposing factions was held at Aburi, Ghana, beginning 4 January 1967. There, they agreed to a confederal system of government. This agreement was never implemented, as a consequence, after failed efforts to negotiate peace, on 30 May 1967, Lieutenant Colonel Chukumeka Odumegwu Ojukwu, Eastern Military Governor, unilaterally declared independence from Nigeria. The new independent nation was called Biafra after the Bight of Biafra, also called the Bight of Bonny (a "bight" is a geographical feature that is defined as a large, sheltered, shallow bay). The Biafran/Nigerian Civil War had begun. The war was executed mostly in Biafran territory in the southeast leading to massive civilian deaths and property destruction. Strongly outnumbered and fighting against superior technology, the Biafrans were encircled, isolated and blockaded by the nationalist Nigerian forces. The consequence was starvation, mass death, and displacement of Igbos. With the Nigerian blockade cutting off the Biafrans from their expected source of oil revenue from the Rivers state, the Biafrans suffered loss of life and malnutrition. For a variety of state reasons, global humanitarian aid was scarce and inadequate, leaving Biafrans without food, medicines, or clothing.

The Nigerian conquest of the city of Owerri on 6 January 1970 signaled the collapse of Biafra's resistance, ending their Civil War. Lieutenant Colonel Chukumeka Odumegwu Ojukwu, the leader who in 1967 declared their secession, fled to the Ivory Coast. On 12 January 1970 Biafran Chief of Army Staff Major General Phillip Effiong surrendered to the Nigerian government, stating Biafra's physical and psychological surrender: "We are firm, we are loyal Nigerian citizens and accept the authority of the Federal Military Government. We accept the existing administrative and political structure of the federation of Nigeria. The Republic of Biafra hereby ceases to exist" (Oko qtd. in "Genocide and Crimes Against Humanity"). Colonel Yakubu Dan-Yumma Gowon, Nigeria's new head of state, accepted Biafra's unconditional surrender and began a Reconciliation, Reconstruction, and Rehabilitation program to insure that, as he declared, there would be no victor and no vanquished. While there was international debate over whether the Nigerian Civil War had represented genocide of the Igbo peoples, it was determined by the international community that, while the death and destruction in Igbo land reached devastating proportions, the intent of the Nigerian government was not systematic destruction of a targeted people in genocide, as had occurred in Rewanda and Germany, but rather a determined effort to end secession and thereby preserve a unified nation of Nigeria, as occurred in the American Civil War.

The outcomes of the Civil War's aftermath in the Reconciliation, Reconstruction, and Rehabilitation program achieved some of the desperately overdue goals of a unified Nigeria, though fulfillment of promises was aborted by subsequent corruption and further military coups:

• resettlement of displaced Igbos in permanent residences
• physical, emotional, and political rehabilitation of soldiers and civilians
• reconstruction of destroyed infrastructure (roads, railways, communications, etc) and public buildings
• correction of economic and social problems of poverty, malnourishment, disease (especially preventable disease), ignorance and lack of educational opportunities (in contrast to the abundant opportunities in the Southern area)
• war relief food, medicine, shelter
• establishment of civilian government and extinguishing of military government on 1 October 1975
• well operated, non-controversial national census
• draft a new national constitution
• hold honest elections
• creation of states according to the 1967 agreement on implementing a confederal system of government

Source: "Biafra/Nigeria." "Genocide and Crimes Against Humanity." Ed. Dinah L. Shelton. Vol. 1. Gale Cengage, 2005

In a sense, you can say that the British were the cause of the Biafran Civil War which happened in Nigeria from 1967 to 1970.  It was British colonialism which was the ultimate cause of the war.

When the British (along with other European nations) colonized Africa, it split its territories on that continent up into different colonies based on its own interests.  In other words, Britain did not go around figuring out which areas really belonged together.  Instead, they simply drew lines on the map, creating new political entities that had never existed before.  Nigeria was one such entity.

When the British drew the map of what would become Nigeria, they included areas that were dominated by a variety of different ethnic groups.  Two of the main ethnic groups whose areas were lumped together into Nigeria were the Hausa and the Igbo.  There were many differences between these groups.  For example, the Hausa were Muslim and had a system of government that was relatively feudal.  By contrast, the Igbo were mainly Christian and had a more democratic society.  These two groups did not have any natural ties that would make it reasonable to put them together into one country.  However, the British lumped them together, creating Nigeria.

In 1960, Nigeria became independent.  This led to conflicts between the Hausa and the Igbo as to who should have power in the new country.  The conflicts between them eventually led the Igbos in the Southeast to secede from Nigeria.  They formed a new country that they called Biafra.  The war was fought to prevent the secession and to force that region back into the country of Nigeria.

The war was successful and Nigeria returned to its previous boundaries.  However, the conflicts between the ethnic groups did not stop.  Even today, there are conflicts between these groups.  These conflicts help to make Nigeria somewhat politically unstable and they help to retard its economic and political development.

Thus, the cause of the war was the ethnic conflict in Nigeria.  The main outcome was that Nigeria remained a single country with rival ethnic groups who still do not get along very well with one another.