This is a chronology of main political events in Nigeria, sub-Saharan Africa's most populous country, since independence.
1 OCTOBER 1960 - Nigeria gains independence from Britain. Abubakar Tafawa Balewa of the Northern Peoples Congress emerges as prime minister. Nnamdi Azikiwe of the National Council for Nigerian Citizens becomes the first Nigerian governor-general and the country’s first president when Nigeria becomes a republic in 1963. Obafemi Awolowo of the Action Group becomes leader of the opposition.
15 JANUARY 1966 - Prime Minister Balewa is killed in a failed coup led by mostly Igbo army officers. Many other top members of the government are also killed, including the powerful premier of the Northern Region, Ahmadu Bello. The government collapses and the most senior army officer, Gen Thomas Aguiyi-Ironsi, takes over as head of state.
29 JULY 1966 - Northern army officers stage a ‘counter-coup’. Head of state Maj-Gen Aguiyi-Ironsi is killed and Col Yakubu Gowon emerges as the new military ruler. Col Emeka Odumegwu-Ojukwu, governor of the Eastern Region, refuses to accept President Gowon’s authority. Igbos and other southeasterners are massacred across the north.
27 MAY 1967 - After several months of political crisis President Gowon announces the dissolution of Nigeria’s four administrative regions and their replacement by a 12-state structure.
30 MAY 1967 - Ojukwu declares the former Eastern Region the independent Republic of Biafra. From this point on Nigeria is technically at war.
12 JANUARY 1970 - Biafra surrenders. More than one million people had died in 30 months of civil war – most from starvation. President Gowon declares “no victor, no vanquished” and announces a programme of reconstruction and rehabilitation.
29 JULY 1975 - President Gowon is toppled by Maj-Gen Murtala Mohammed while attending an Organisation of African Unity summit in Kampala, Uganda. He goes into exile in Britain.
13 FEBRUARY 1976 - Head of state Maj-Gen Mohammed is assassinated in an aborted coup. His next in command, Maj-Gen Olusegun Obasanjo, becomes head of state.
1 OCTOBER 1979 - Gen Obasanjo hands over power to President Shagari, who won that year's elections on the platform of the National Party of Nigeria, bringing an end to 13 years of military rule.
31 DECEMBER 1983 - President Shehu Shagari is toppled in a military coup three months after winning a second term at elections marred by violence and allegations of widespread rigging. The new military ruler is Maj-Gen Muhammadu Buhari.
27 AUGUST 1985 - President Buhari is overthrown by his army chief, Maj-Gen Ibrahim Babangida, who makes it clear from the outset that he prefers the title of president.
22 April 1990 - President Babangida survives a bloody coup attempt by mainly junior army officers. In the courts martial that follow more than 200 soldiers are sentenced to death and executed.
12 JUNE 1993 - Nigerians vote in presidential elections to end military rule. The candidates are Moshood Abiola of the Social Democratic Party and Bashir Tofa of the National Republican Convention. Early results show Abiola with a runaway lead.
15 JUNE 1993 - The electoral commission suspends publication of the results of elections, citing a need to obey a pre-election ruling by a court, which had ordered that the election should not be held. The commission had earlier disobeyed the court ruling because the military decree empowering the election had stripped the courts of their powers to accept election-related lawsuits.
23 JUNE 1993 - A statement from Gen Babangida's office declares the elections annulled. For the next two months massive demonstrations organised by pro-democracy activists paralyse several Nigerian cities.
27 AUGUST 1993 - President Babangida steps down as president under intense pressure. He hands over to an interim government headed by Ernest Shonekan, a civilian businessman he handpicked and mandated to organise fresh elections.
17 NOVEMBER 1993 - The interim government is toppled by the defence minister, Gen Sani Abacha. He dissolves all civilian institutions, including the national legislature and state governments.
10 NOVEMBER 1995 - Renowned writer and environmental campaigner, Ken Saro-Wiwa, is executed along with eight other Ogoni minority rights activists on murder charges, after a trail generally perceived to be flawed. The execution draws international outrage and the Abacha regime becomes an international pariah.
8 JUNE 1998 - President Abacha suddenly dies of apparent heart failure. He is succeeded by the most senior military officer, Gen Abdulsalami Abubakar, who pledges rapid reforms to restore democracy.
15 JUNE 1998 - President Abubakar frees former military ruler Gen Obasanjo from jail where he was serving a 15-year term. He had been convicted in 1995 along with several military officers and civilians on what was believed by many Nigerians to be trumped-up charges of plotting Abacha’s fall.
7 JULY 1998 - Chief Moshood Abiola, who had been detained by former president Abacha since 1994 for laying claims to the presidency on the basis of the annulled 1993 vote, dies in detention of apparent heart failure. His release was being prepared by the Abubakar regime.
23 FEBRUARY 1999 - Nigerians vote in presidential elections. The candidates are former president Obasanjo of the People’s Democratic Party and Olu Falae, the joint candidate of the Alliance for Democracy and the All People’s Party. Obasanjo emerges victorious, winning nearly 70 percent of the vote.
29 MAY 1999 - President Obasanjo is sworn in and a new civilian government is inaugurated, ending more than 15 years of domination of power by unelected military rulers.
19 DECEMBER 1999 - President Obasanjo orders troops to raid the town of Odi in the Niger Delta after armed militants killed 12 policemen. The troops level the town, destroying every building except a bank and a church. Rights groups say more than 1,000 people were killed.
27 JANUARY 2000 - Northern Zamfara state starts the implementation of Shari’ah law, requiring amputations of limbs for stealing, public flogging for drinking alcohol and stoning to death for adultery. Over the next two years 11 other states in the mainly Muslim north also adopt Shari’ah.
21 FEBRUARY 2000 - Sectarian riots break out in the northern city of Kaduna over moves by the state government to introduce the strict Islamic legal code, Shari’ah, in the city split between Christians and Muslims. More than 2,000 people are killed over five days of fighting. Reprisal killings targeting Muslims break out in several cities in the mainly Christian southeast.
29 MAY 2003 - President Obasanjo is sworn in for a second and final four-year term in office after elections international and local observers said were marred by widespread ballot rigging and irregularities.
22 OCTOBER 2003 - Nigerian troops launch military operations in several villages in Benue state on President Obasanjo’s orders, killing hundreds of civilians in reprisal for the killing of 19 soldiers by a local militia.
16 MAY 2006 - Senate votes against a proposal to remove constitutional term limits; thus President Olusegun Obasanjo cannot run for a third term.
15 MARCH 2007 - The Independent National Electoral Commission releases the names of 24 candidates cleared to run for the presidency in the 2007 general elections. The list excludes Vice President Atiku Abubakar, who left the ruling party to become an opposition candidate.