<Tr> <Th> </Th> <Td> </Td> <Td> Nnamdi Azikiwe (1904--1996) </Td> <Td> 1 October 1963 </Td> <Td> 16 January 1966 (deposed .) </Td> <Td> 2 years, 107 days </Td> <Td> National Council of Nigeria and the Cameroons </Td> <Td> Balewa </Td> </Tr> <P> Major Chukwuma Kaduna Nzeogwu led a coup d'état in 1966 which overthrew President Azikiwe and his government . </P> <Table> <Tr> <Th_colspan="3"> Head of State </Th> <Th_colspan="3"> Term of Office </Th> <Th> Military </Th> </Tr> <Tr> <Th> No </Th> <Th> Portrait </Th> <Th> Name </Th> <Th> Took Office </Th> <Th> Left Office </Th> <Th> Duration </Th> </Tr> <Tr> <Th> </Th> <Td> </Td> <Td> Major - General Johnson Aguiyi - Ironsi (1924--1966) </Td> <Td> 16 January 1966 </Td> <Td> 12 July 1966 (assassinated .) </Td> <Td> 177 days </Td> <Td> Federal Military Government </Td> </Tr> <Tr> <Th> </Th> <Td> </Td> <Td> General Yakubu Gowon (1934--) </Td> <Td> 1 August 1966 </Td> <Td> 29 July 1975 (deposed .) </Td> <Td> 8 years, 362 days </Td> <Td> Federal Military Government </Td> </Tr> <Tr> <Th> </Th> <Td> </Td> <Td> General Murtala Mohammed (1938--1976) </Td> <Td> 29 July 1975 </Td> <Td> 13 February 1976 (assassinated .) </Td> <Td> 199 days </Td> <Td> Federal Military Government </Td> </Tr> <Tr> <Th> 5 </Th> <Td> </Td> <Td> Major - General Olusegun Obasanjo (1937--) </Td> <Td> 13 February 1976 </Td> <Td> 1 October 1979 (resigned .) </Td> <Td> 3 years, 258 days </Td> <Td> Federal Military Government </Td> </Tr> </Table> <Tr> <Th_colspan="3"> Head of State </Th> <Th_colspan="3"> Term of Office </Th> <Th> Military </Th> </Tr>

Who was the first military head of state in nigerian