Boko Haram insurgency insurgency spread to neighboring Cameroon, Chad, and Niger thus becoming a major regional conflict. In 2015, a coalition offensive forced Boko Haram to retreat into the Sambisa Forest. The insurgency took place within the context of long-standing issues of religious violence between Nigeria's Muslim and Christian communities. Boko Haram has been called the world's deadliest terrorist group, in terms of the number of people it has killed. Nigeria was amalgamated both the Northern and Southern protectorate in 1914, only about a decade after the defeat of the Sokoto Caliphate and other Islamic states by the British which were to constitute
Boko Haram later, Shekau refused to accept al-Barnawi's appointment as leader and vowed to fight him while stating that he was still loyal to ISIL's leader Abu Bakr al-Baghdadi. The group has since split into pro-Barnawi and pro-Shekau factions, with reports of armed clashes breaking out between them. Shekau has released videos since the split in which he refers to his group by its previous name of "Jamatu Ahlis Sunna Lidawatti wal Jihad". On 23 August 2016, the Nigerian Army announced it conducted an overnight air-operation that was 'very successful' in killing the leadership of Boko Haram. Among those presumed killed was