Rashin jituwa da rikice-rikice na zaɓe da tsarin siyasa ya faru, a cikin 1966, ƙungiyoyin soja na baya-baya. Juyin mulkin farko ya kasance a cikin watan Janairun 1966, kuma yawancin sojojin Igbo ne ke jagorantar su, ƙarƙashin Majors EMMANUEL IFEAJUNA da CHUKWUMA KADUNA NZEOGWU. Masu shirya juyin mulkin sun yi nasarar kashe SIR. AHMADU BELLO da ABUBAKAR TAFAWA ƁALEWA tare da manyan shugabannin yankin Arewa da kuma Primier SAMA’ILA AKINTOLA na Yammacin Yamma, amma waɗanda suka yi juyin mulkin sun yi ƙoƙarin kafa gwamnatin haɗaka. Shugaban Majalisar Dattawa NWAFOR ORIZU ya miƙa ragamar mulki ga Sojoji, sannan a ƙarƙashin umarnin wani jami’in Igbo, Janar JOHNSON AGUIYI-IRONSI.
Daga baya, juyin mulkin da aka yi a shekarar 1966, wanda ya samu goyon baya daga hannun jami’an soji na Arewacin ƙasar, ya kawo sauyin YAKUBU GOWON a matsayin shugaban mulkin soja. Tashin hankali ya tashi tsakanin Arewa da Kudu; Sannan Igbo a biranen Arewacin na fama da zalunci kuma yawancinsu sun gudu zuwa yankin Gabashi
A watan Mayun shekarar 1967, Gwamnan Yankin Gabashin Laftanar Kanar EMEKA OJUKWU ya ayyana yankin a mai ‘yanci, a matsayin wata ƙasa da ake kira Jamhuriyar BIAFRA, a ƙarƙashin jagorancinsa. Wannan shelar ta haifar da yaƙin basasa na Nijeriya, wanda ya fara a yayin da ɓangaren gwamnatin Nijeriya ke yakar Biafra a ranar 6 ga Yulin 1967 a Garkem. Yaƙin na watanni 30, tare da tsawan dogon yaƙi na Biafra da keɓewa daga kasuwanci da kayayyaki, ya ƙare a cikin Janairu 1970.
Adadin waɗanda suka mutu a tsohuwar Yankin Gabas yayin yaƙin basasa na watanni 30 ya kai daga miliyan ɗaya zuwa uku. Faransa, Misira, Tarayyar Soviet, Burtaniya, Isra’ila, da sauransu sun shiga cikin yaƙin basasa a bayan al’amuran. Burtaniya da Tarayyar Soviet su ne manyan masu goyon bayan gwamnatin Nijeriya; tare da Nijeriya ta yi amfani da tallafin iska daga matukan jirgin saman Masar wanda Gamal Abdel Nasser ya bayar, yayin da Faransa da Isra’ila suka tallafa wa Biafra. Gwamnatin Kongo, a karkashin Shugaba Joseph-Désiré Mobutu, ta yi tsayin daka kan matakin kafa kasar Biafra, tana mai bayyana cikakken goyon baya ga Gwamnatin Tarayyar Nijeriya, tare da tura dubunnan dakaru don yin yaƙi da masu ɓallewa.
Bayan yaƙin, Nijeriya ta ji daɗin hauhawar mai a shekarun 1970, a lokacin ne ƙasar ta shiga OPEC da karɓar kuɗin mai mai yawa. Duk da waɗannan kuɗaɗen shiga, gwamnatin soja ta yi kaɗan ta inganta daidaiton rayuwar mazauna, taimaka wa ƙananan kamfanoni da matsakaita, ko saka jari a harkar. Yayin da kuɗaɗen shiga na man fetur ke ƙara hauhawa,hauhawar tallafin tarayya zuwa jihohi, gwamnatin tarayya ta zama cibiyar gwagwarmayar siyasa da kuma kusan karfin iko a kasar. Yayin da samar da mai da kuma kuɗaɗen shiga ya ƙaru, gwamnatin Nijeriya ta zama mai dogaro da kuɗaɗen shiga na mai da kasuwancin kayayyakin masarufi na kasa da kasa, saboda damuwa game da kasafin kuɗi da tattalin arziki. Juyin mulkin a watan Yulin 1975, ƙarƙashin jagorancin Janar SHEHU MUSA YAR’ADUA da JOSEPH GARBA suka hamɓarar da Gowon, waɗanda suka gudu zuwa Biritaniya.Waɗanda suka yi juyin mulkin suna son maye gurbin mulkin Gowon ne da wasu janar-janar uku waɗanda Kwamitin Sojoji zai iya bijiro da hukuncin. A saboda wannan nasarar, sun shawo kan Janar MURTALA MUHAMMAD ya zama shugaban mulkin soja, tare da Janar OLUSEGUN OBASANJO a matsayin janar na biyu, da Janar THEOPHILUS ƊANJUMA a matsayin na uku. Tare da haɗin gwuiwa, sun gabatar da matakan tallafi na daƙile hauhawar farashin kaya, da kafa Ofishin Bincike na Yankin Cin Hanci, da maye gurbin duk gwamnonin soja da sabbin jami’ai, tare da ɓullo da “Operation Deadwood” ta hanyar da suka kori jami’ai 11,000 daga aikin farar hula.
Kanar BUKA SUKA DIMKA ya ƙaddamar da juyin mulkin a watan Fabrairun 1976 a kan Gwamnatin Nijeriya, lokacin da aka kashe Janar Murtala Mohammed. Dimka ya rasa cikakken goyon baya a tsakanin sojoji da juyin mulkin da ya yi, kuma hakan ya tilasta shi tserewa. Bayan yunƙurin juyin mulki, an naɗa Janar Olusegun Obasanjo a matsayin shugaban mulkin soja. A matsayinsa na shugaban ƙasa, Obasanjo ya yi alƙawarin ci gaba da manufofin Murtala. Sanin hatsarin dake tattare da raba kawunan ‘yan Arewacin Nijeriya, Obasanjo ya kawo Janar Shehu Yar’Adua a matsayin wanda zai maye gurbinsa da kuma muƙami na biyu a matsayin shugaban Ma’aikata, Babban hedikwatar da ta kammala aikin soja, tare da Obasanjo a matsayin shugaban ƙasa, da Janar Theophilus Ɗanjuma a matsayin Babban Ma’aikatan Soja, ukun sun ci gaba da ƙoƙarin sake ƙwace iko da tsarin mulkin soja da tsara yadda za a sauya tsarin mulkin soja: jihohi da ƙirƙirar ƙasa, sake fasalin ƙananan hukumomi da kwamitin tsara kundin tsarin mulkin Jamhuriyyar Nijeriyar
