This article attempts to explain the apparent failure of Nigeria’s military action against the Boko Haram (roughly translated as ‘Western education is prohibited’) insurgency in the north-east of the country. Until the involvement of troops from Chad and Niger in January 2015, the Boko Haram insurgents were succeeding in their effort to establish, or rather consolidate, an extreme version of the ‘Islamic state’ in parts of north-east Nigeria. For over five years, the military struggled to defend the sovereignty and territorial integrity of Nigeria against Boko Haram, with little success. The war opened a Pandora’s box, exposing a deep crisis in the military and the civilian leadership in Nigeria. The Boko Haram insurgents were able to fly the flag of their ‘state’ in the territory of Nigeria. This article argues that the failure of the military action can be attributed to three factors: the erosion of military professionalism under civilian administrations since 1999, the poor handling of the war by the top military officers, and a lack of decisiveness in the leadership of President Jonathan and the military to end the insurgency.