The Boko Haram insurgency began in 2009, when the jihadistgroupBoko Haram started an armed rebellion against the government of Nigeria. The conflict takes place within the context of long-standing issues of religious violence between Nigeria's Muslim and Christian communities, and the insurgents' ultimate aim is to establish an Islamic state in the region.
Boko Haram's initial uprising failed, and its leader Mohammed Yusuf was killed by the Nigerian government. The movement consequently fractured into autonomous groups and started an insurgency, though rebel commander Abubakar Shekau managed to achieve a kind of primacy among the insurgents. Though challenged by internal rivals, such as Abu Usmatul al-Ansari's Salafist conservative faction and the Ansaru faction, Shekau became the insurgency's de facto leader and mostly kept the different Boko Haram factions from fighting each other, instead focusing on overthrowing the Nigerian government. Supported by other Jihadist organizations such as al-Qaeda and Al-Shabaab, Shekau's tactics were marked by extreme brutality and explicit targeting of civilians.
After years of fighting, the insurgents became increasingly aggressive, and started to seize large areas in northeastern Nigeria. The violence escalated dramatically in 2014, with 10,849 deaths, while Boko Haram drastically expanded its territories. At the same time, the insurgency spread to neighboring Cameroon, Chad, and Niger, thus becoming a major regional conflict. Meanwhile, Shekau attempted to improve his international standing among Jihadists by tacitly aligning with the Islamic State of Iraq and the Levant (ISIL) in March 2015, with Boko Haram becoming the "Islamic State's West Africa Province" (ISWAP).
The insurgents were driven back during the 2015 West African offensive by a Nigeria-led coalition of African and Western states, forcing the Islamists to retreat into Sambisa Forest and bases at Lake Chad. Discontent about various issues consequently grew among Boko Haram. Dissidents among the movement allied themselves with ISIL's central command and challenged Shekau's leadership, resulting in a violent split of the insurgents. Since then, Shekau and his loyalist group are generally referred to as "Boko Haram", whereas the dissidents continued to operate as ISWAP under Abu Musab al-Barnawi. The two factions consequently fought against each other while waging insurgencies against the local governments. After a period of reversals, Boko Haram and ISWAP launched new offensives in 2018 and 2019, again growing in strength.
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 much of Northern Nigeria. Sir Frederick Lugard assumed office as governor of both protectorates in 1912. The aftermath of the First World War saw Germany lose its colonies, one of which was Cameroon, to French, Belgian and British mandates. Cameroon was divided in French and British parts, the latter of which was further subdivided into southern and northern parts. Following a plebiscite in 1961, the Southern Cameroons elected to rejoin French Cameroon, while the Northern Cameroons opted to join Nigeria, a move which added to Nigeria's already large Northern Muslim population. The territory made up much of what is now Northeastern Nigeria, and a large part of the areas affected by the insurgency.
In the late 1970s and early 1980s, there was a major Islamic uprising led by Maitatsine (Mohammed Marwa) and his followers, Yan Tatsine that led to several thousand deaths. After Maitatsine's death in 1980, the movement continued some five years more.
Since the return of democracy to Nigeria in 1999, Sharia has been instituted as a main body of civil and criminal law in 9 Muslim-majority and in some parts of 3 Muslim-plurality states, when then-Zamfara State governor Ahmad Rufai Sani began the push for the institution of Sharia at the state level of government. This was followed by controversy as to the would-be legal status of the non-Muslims in the Sharia system. A spate of Muslim-Christian riots soon emerged.
In the primarily Islamic northern states of Nigeria, a variety of Muslim groups and populations exist, who favour the nationwide introduction of Sharia Law. The demands of these populations have been at least partially upheld by the Nigerian Federal Government in 12 states, firstly in Zamfara State in 1999. The implementation has been widely attributed as being due to the insistence of Zamfara State governor Ahmad Rufai Sani.
The death sentences of Amina Lawal and Safiya Hussaini attracted international attention to what many saw as the harsh regime of these laws. These sentences were later overturned; the first execution was carried out in 2002.
Twelve out of Nigeria's thirty-six states have Sunni Islam as the dominant religion. In 1999, those states chose to have Sharia courts as well as Customary courts. A Sharia court may treat blasphemy as deserving of several punishments up to, and including, execution. In many predominantly Muslim states, conversion from Islam to another religion is illegal and often a capital offence.
According to a Nigerian study on demographics and religion, Muslims make up 50.5% of the population. Muslims mainly live in the north of the country; the majority of the Nigerian Muslims are Sunnis. Christians are the second-largest religious group and make up 48.2% of the population. They predominate in the central and southern part of the country.
For reasons of avoiding political controversy, questions of religion were forgone in the 2006 Nigerian census.
Boko Haram conducted its operations more or less peacefully during the first seven years of its existence. That changed in 2009 when the Nigerian government launched an investigation into the group's activities following reports that its members were arming themselves. Prior to that the government reportedly repeatedly ignored warnings about the increasingly militant character of the organisation, including that of a military officer.
When the government came into action, several members of the group were arrested in Bauchi, sparking deadly clashes with Nigerian security forces which led to the deaths of an estimated 700 people. During the fighting with the security forces Boko Haram fighters reportedly "used fuel-laden motorcycles" and "bows with poison arrows" to attack a police station. The group's founder and then leader Mohammed Yusuf was also killed during this time while still in police custody. After Yusuf's killing, Abubakar Shekau became the leader and held this position in January 2015.
After the killing of M. Yusuf, the group carried out its first terrorist attack in Borno in January 2010. It resulted in the killing of four people. Since then, the violence has only escalated in terms of both frequency and intensity. In September 2010, a Bauchi prison break freed more than 700 Boko Haram militants, replenishing their force.
15 June 2011 also marked the start of a Federal Government sanctioned military effort to counter the growing threat of Boko Haram's insurgency. With 21 Armoured Brigade (21 Bde) of the Nigerian Army as its nucleus, Joint Task Force Operation Restore Order (JTF ORO 1) marked the start of the Army's lengthy counter-insurgency (COIN) campaign against Boko Haram. The campaign has gone through several phases and has greatly escalated in scale, capacity, components and stakeholders, since that time. Results, however, have sometimes been mixed and the Army has been criticised for being too kinetic in its COIN.
In January 2012, Abubakar Shekau, a former deputy to Yusuf, appeared in a video posted on YouTube. According to Reuters, Shekau took control of the group after Yusuf's death in 2009. Authorities had previously believed that Shekau died during the violence in 2009. By early 2012, the group was responsible for over 900 deaths. On 8 March 2012, a small Special Boat Service team and the Nigerian Army attempted to rescue two hostages, Chris McManus and Franco Lamolinara, being held in Nigeria by members of the Boko Haram terrorist organisation loyal to al-Qaeda. The two hostages were killed before or during the rescue attempt. All the hostage takers were reportedly killed.
2013 government offensive
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In May 2013, Nigerian government forces launched an offensive in the Borno region in an attempt to dislodge Boko Haram fighters after a state of emergency was called on 14 May 2013. The state of emergency, which was still in force in May 2014, applied to the states of Borno, Yobe, and Adamawa in northeastern Nigeria. The offensive had initial success, but the Boko Haram rebels were able to regain their strength. In July 2013, Boko Haram massacred 42 students in Yobe, bringing the school year to an early end in the state. On 5 August 2013, Boko Haram launched dual attacks on Bama and Malam Fatori, leaving 35 dead. On 11 August, BH killed 44 people in a mass shooting at a mosque in Konduga, Borno State.
On 15 April 2014, terrorists abducted about 276 female students from a college in Chibok in Borno state. The abduction was widely attributed to Boko Haram. It was reported that the group had taken the girls to neighbouring Cameroon and Chad where they were to be sold into marriages at a price below a Dollar. The abduction of another eight girls was also reported later. These kidnappings raised public protests, with some protesters holding placards bearing the Twitter tag #BringBackOurGirls which had caught international attention.The Guardian reported that the British Royal Air Force conducted Operation Turus in response the Chibok schoolgirls kidnapping by Boko Haram in Nigeria in April 2014. A source involved with the Operation told The Observer that "The girls were located in the first few weeks of the RAF mission", and that "We [RAF] offered to rescue them, but the Nigerian government declined", this was because it viewed any action to be taken as a "national issue", and for it to be resolved by Nigerian intelligence and security services, the source added that the girls were then tracked by the aircraft as they were dispersed into progressively smaller groups over the following months. Several countries pledged support to the Nigerian government and to help their military with intelligence gathering on the whereabouts of the girls and the operational camps of Boko Haram.
On 20 May 2014, a total of two bombs in the city of Jos, Plateau State, Nigeria, were detonated, resulting in the deaths of at least 118 people and the injury of more than 56 others. The bombs detonated 30 minutes apart, one at a local market place at approximately 3:00 and the second in a parking lot next to a hospital at approximately 3:30, where rescuers responding to the first accident were killed. Though no group or individual has claimed responsibility, the attacks have been attributed to Boko Haram.
First responders were unable to reach the scenes of the accidents, as "thousands of people were fleeing the scene in the opposite direction". The bombs had been positioned to kill as many people as possible, regardless of religion, which differed from previous attacks in which non-Muslims were targeted. The bombers were reported to have used a "back-to-back blast" tactic, in which an initial bomb explodes at a central location and another explodes a short time later with intent to kill rescue workers working to rescue the wounded.
Escalation in fighting
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Victims of a Boko Haram bombing in November 2014
Starting in late 2014, Boko Haram militants attacked several Nigerian towns in the North and captured them. This prompted the Nigerian government to launch an offensive, and with the help of Chad, Niger, and Cameroon, they have recaptured many areas that were formerly under the control of Boko Haram.
In late 2014, Boko Haram seized control of Bama, according to the town's residents. In December 2014, it was reported that "people too elderly to flee Gwoza Local Government Area were being rounded up and taken to two schools where the militants opened fire on them." Over 50 elderly people in Bama were killed. A "gory" video was released of insurgents shooting over a hundred civilians in a school dormitory in the town of Bama.
On 10 January 2015, a bomb attack took place at the Monday Market in Maiduguri, killing 19 people. The city is considered to be at the heart of the Boko Haram insurgency. In the early hours of 25 January 2015, Boko Haram launched a major assault on the city. On 26 January 2015, CNN reported that the attack on Maiduguri by "hundreds of gunmen" had been repelled, but the nearby town of Monguno was captured by Boko Haram. The Nigerian Army claimed to have successfully repelled another attack on Maiduguri on 31 January 2015.
Map of Boko Haram's territorial control on 10 April 2015, over 2 months after the start of the 2015 West African offensive
Starting in late January 2015, a coalition of military forces from Nigeria, Chad, Cameroon, and Niger began a counter-insurgency campaign against Boko Haram. On 4 February 2015, the Chad Army killed over 200 Boko Haram militants. Soon afterwards, Boko Haram launched an attack on the Cameroonian town of Fotokol, killing 81 civilians, 13 Chadian soldiers and 6 Cameroonian soldiers. On 17 February 2015, the Nigerian military retook Monguno in a coordinated air and ground assault.
On 7 March 2015, Boko Haram's leader Abubakar Shekau pledged allegiance to the Islamic State of Iraq and the Levant (ISIL) via an audio message posted on the organisation's Twitter account. Nigerian army spokesperson Sami Usman Kukasheka said the pledge was a sign of weakness and that Shekau was like a "drowning man". That same day, five suicide bomb blasts left 54 dead and 143 wounded. On 12 March 2015, ISIL's spokesman Abu Mohammad al-Adnani released an audiotape in which he welcomed the pledge of allegiance, and described it as an expansion of the group's caliphate to West Africa.
Following its declaration of loyalty to ISIL, Boko Haram was designated as the group's "West Africa Province" (Islamic State West Africa Province, or ISWAP) while Shekau was appointed as its first vali (governor). Furthermore, ISIL started to support Boko Haram, but also began to interfere in its internal matters. For example, ISIL's central leadership attempted to reduce Boko Haram's brutality toward civilians and internal critics, as Shekau's ideology was "too extreme even for the Islamic State".
On 24 March 2015, residents of Damasak, Nigeria said that Boko Haram had taken more than 400 women and children from the town as they fled from coalition forces. On 27 March 2015, the Nigerian army captured Gwoza, which was believed to be the location of Boko Haram headquarters. On election day, 28 March 2015, Boko Haram extremists killed 41 people, including a legislator, to discourage hundreds from voting.
In March 2015, Boko Haram lost control of the Northern Nigerian towns of Bama and Gwoza (believed to be their headquarters) to the Nigerian army. The Nigerian authorities said that they had taken back 11 of the 14 districts previously controlled by Boko Haram. In April 2016, four Boko Haram camps in the Sambisa Forest were overrun by the Nigerian military who freed nearly 300 females. Boko Haram forces were believed to have retreated to the Mandara Mountains, along the Cameroon–Nigeria border. On 16 March 2015, the Nigerian army said that it had recaptured Bama. On 27 March 2015, the day before the Nigerian presidential election, the Nigerian Army announced that it had recaptured the town of Gwoza from Boko Haram.
By April 2015, the Nigerian military was reported to have retaken most of the areas previously controlled by Boko Haram in Northeastern Nigeria, except for the Sambisa Forest.
In May 2015, the Nigerian military announced that they had released about 700 women from camps in Sambisa Forest.
In August 2015, it was reported that over one thousand deaths had occurred since the inauguration of the new administration.
On 28 October 2015, it was announced that Nigerian troops have rescued 338 people from Boko Haram near the group's Sambisa Forest stronghold. Of those rescued, 192 were children and 138 were women.
In December 2015, Muhammadu Buhari, the President of Nigeria, claimed that Boko Haram was "technically defeated" and it was reported that 1,000 women had been rescued from Boko Haram in January 2016.
American military support
In early October 2015, the US military deployed 300 troops to Cameroon, with the approval of the Cameroonian government, with the primary mission of providing intelligence support to local forces, and conducting reconnaissance flights.
The troops are also overseeing a program to transfer American military vehicles to the Cameroonian Army to aid in their fight against Islamist militants.
As of May 2016, U.S. personnel are involved in drone operations from Garoua to help provide intelligence in the region to assist local forces. There are additional drone operations based out of Niger. U.S. Army soldiers in Cameroon are also providing IED awareness training to the country's infantry forces.
In March 2016, Boko Haram was reported to have used islands in Lake Chad as bases.
As Boko Haram's power waned, Shekau's leadership was increasingly criticised among Boko Haram and ISIL's central command. These elements repeatedly attempted to convince Shekau to change his tactics or his extreme ideas (such as considering everyone an apostate who has not openly sided with him, including all Muslims). Shekau refused to budge, and openly disobeyed ISIL's "Caliph" Abu Bakr al-Baghdadi in regard to various matters. ISIL and parts of Boko Haram eventually came to the conclusion that this was no longer tolerable, whereupon Shekau was removed from his position as vali of ISIL's West Africa Province in August 2016. Abu Musab al-Barnawi, a son of Boko Haram founder Mohammed Yusuf was appointed as his successor. This event resulted in an open split among the Nigerian insurgents. Shekau refused to accept his dismissal, rallied a large number of supporters and violently opposed Barnawi and ISIL's central command. In turn, Barnawi and those who were loyal to him declared Shekau's group Khawarij. The two insurgent factions subsequently became fully separate organizations, with Shekau's followers re-adopting their old name "Jamā'at Ahl as-Sunnah lid-Da'wah wa'l-Jihād" (outsiders refer to this faction as "Boko Haram"), whereas Barnawi's forces continued to operate as "Islamic State's West Africa Province" (ISWAP). The two groups are generally hostile and fight each other, though it is possible that they occasionally cooperate against their common enemies.
On 31 August 2016, Major General Lucky Irabor stated that the militants now only controlled a few villages and towns near Lake Chad and in Sambisa forest. He further stated that the military expected recapturing the final strongholds of the group within weeks.
On 24 December 2016, President Muhammadu Buhari declared that Boko Haram had been ousted from their last stronghold in the Sambisa Forest, effectively reducing Boko Haram to an insurgent force. This victory left Boko Haram without any territorial holdings; however, Boko Haram still maintains an extensive ability to carry out attacks.
On 7 January 2017, a group of Boko Haram militants attacked a Nigerian army base in Yobe State, killing five soldiers. In response, the Nigerian Army launched retaliatory strikes and killed 15 militants.
On 18 March 2017, at least six people were killed and 16 wounded after four female suicide bombers blew themselves up on the outskirts of Maiduguri city.
On 22 March 2017, the Nigerian Department of State Services (DSS) announced that a suspected member of Boko Haram had been arrested in northeastern Yobe State. The suspect confessed details of a plot to attack the American and British embassies, and other western targets in Abuja. The DSS also later announced that between 25 and 26 March 2017, five suspected members of Boko Haram had been arrested, thus thwarting the plot.
On 2 April 2017, the Nigerian military began what it said was its "final offensive" to retake Boko Haram's last strongholds.
On 17 May 2017, the Nigerian Army reported that it had arrested about 126 suspected Boko Haram terrorists at the Internally Displaced Persons (IDPs) camp in Damboa, Borno State.
In September 2017, Boko Haram militants kidnapped about 40 young adults, women and children and killed 18 in the town of Banki, 130 km southeast of Maiduguri, Borno State, on the border of Nigeria and Cameroon. Boko Haram was reported to have killed 380 people between April and September 2017 in the Lake Chad area . About 57% of all schools in Borno state were closed due to the Boko Haram insurgency, affecting the education of about 3 million children.
In December 2017, fighters who were believed to belong to ISWAP attacked a patrol of US Army Special Forces and Nigerian soldiers in the Lake Chad Basin Region in Niger. The coalition troops managed to repel the assault without suffering any casualties.
By March 2018, two main insurgent factions were still active, and continued to wage an insurgency campaign against the government: The followers of Abubakar Shekau (Boko Haram) operated mainly in southern Borno State, while the faction of Abu Musab al-Barnawi (ISWAP) was mostly located around Lake Chad.
On 26 April 2018, Boko Haram bombers killed at least four civilians in the outskirts of Maiduguri, the largest city in Borno State. A subsequent gun battle and tear gas launched by security forces repelled the attackers, but left two officers wounded and several others injured.
On 15 July 2018, hundreds of Nigerian soldiers went missing after ISWAP forces led by Abu Musab al-Barnawi overran a Nigerian army base in the northeastern part of Nigeria. Less than 100 Nigerian soldiers returned after the attack, the attack came 24 hours after ISIL ambushed a military convoy in the neighboring Borno state. The attack on the base resulted in a battle that lasted over an hour, it is unknown if there were any casualties in the assault, a local pro-government militia said the military had sustained some casualties, this attack marks Boko Haram's first major gain since 2015.
On 8 September 2018, ISWAP fighters managed to capture the town of Gudumbali in central Borno, marking their first major gain in nearly two years. The next day, ISIL's West Africa Province released a video showing footage from combat with the Nigerian Army in the area. In late December 2018, ISWAP launched another offensive and captured Baga in northeastern Borno State.
On 18 November 2018, ISWAP fighters attacked a military base in the Nigerian town of Metele, killing at least 118 soldiers while at least 153 others were missing after the attack, the militants also seized tanks, armored vehicles, artillery, weapons, and ammunition.
Barnawi's ISWAP launched a major offensive in January 2019, attacking several Nigerian military bases, including those at Magumeri and Gajiram. Insurgents also overran and destroyed the refugee town of Rann near the border to Cameroon, displacing its inhabitants yet again. The destruction of Rann was initially attributed to ISWAP, but Shekau's Boko Haram later claimed responsibility.
Three Boko Haram suicide bombers killed 30 people in Konduga, Borno State on 16 June 2019. Boko Haram shot dead at least 65 people in Nganzai, Borno, who were walking home from a funeral on 27 July 2019.
Boko Haram bombed a market in Gamboru, Borno, on 6 January 2020, killing at least 30 people. They killed at least 30 people in Auno, Borno on 9 February 2020. They carried out massacres against the Chadian and Nigerian armies on 23 March 2020.
The North consisted of Sahelian states that had long Islamic character. These were feudal and conservative, with rigid caste and class systems and large slave populations. Furthermore, the North failed until 1936 to outlaw slavery. Possibly due to geographical factors, many (but not necessarily all) southern tribes, particularly those on the coast, had made contact with Europeans – unlike the North, which was engaged mainly with the Arab world and not Europe. Due to the system of indirect rule, the British were happy to pursue a limited course of engagement with the Emirs. The traditionalist Northern elites were skeptical of Western education; at the same time their Southern counterparts often sent their sons abroad to study. In time, a considerable developmental and educational gap grew between the South and the North. Even in 2014, Northern states still lagged behind in literacy, school attendance and educational achievement.
Chris Kwaja, a Nigerian university lecturer and researcher, asserted in 2011 that "religious dimensions of the conflict have been misconstrued as the primary driver of violence when, in fact, disenfranchisement and inequality are the root causes". Nigeria, he pointed out, has laws giving regional political leaders the power to qualify people as 'indigenes' (original inhabitants) or not. It determines whether citizens can participate in politics, own land, obtain a job, or attend school. The system is abused widely to ensure political support and to exclude others. Muslims have been denied indigene-ship certificates disproportionately often.
Nigerian opposition leader Buba Galadima said in 2012: "What is really a group engaged in class warfare is being portrayed in government propaganda as terrorists in order to win counter-terrorism assistance from the West."
The conflict has seen numerous human rights abuses conducted by the Nigerian security forces, in an effort to control the violence,
 as well as their encouragement of the formation of numerous vigilante groups (for example, the Civilian Joint Task Force).
Amnesty International accused the Nigerian government of human rights abuses after 950 suspected Boko Harām militants died in detention facilities run by Nigeria's military Joint Task Force in the first half of 2013. As of early 2016, according to Amnesty International, at least 8,000 detainees have died in detention facilities operated by the security services. Furthermore, the Nigerian government has been accused of incompetence and supplying misinformation about events in more remote areas.
Boko Haram has kidnapped several young schoolgirls in Borno, physically, psychologically and sexually abusing them, using and selling them as sex slaves and/or brides of forced marriages with their fighters. – the most famous example being the Chibok kidnapping in 2014. In addition to kidnapping child brides, Human Rights Watch has stated that Boko Harām uses child soldiers, including 12-year-olds. According to an anonymous source working on peace talks with the group, up to 40 percent of the fighters in the group are underage soldiers. The group has forcibly converted non-Muslims to Islam, and is also known to assign non-Kanuris on suicide missions.
Rehabilition of insurgents
A major problem faced by local governments is the rehabilition of captured or surrendered militants, as these are generally suspected by officials and civilians to still hold connections to the rebels and pose a security risk. As result, ex-rebels are often ostracized, which in turn increases the risk of them rejoining the insurgency. Cameroon has planned to construct rehab centers for Boko Haram fighters which are supposed to teach them useful skills to get jobs, and to de-radicalise them. As of February 2019, however, no rehab centers for Boko Haram insurgents had been built yet in Cameroon due to lack of funding.
The insurgence can be seen in the context of other conflicts nearby, for example in the North of Mali. The Boko Harām leadership has international connections to Al-Qaeda in the Islamic Maghreb, Al-Shabaab, the Movement for Unity and Jihad in West Africa (MUJAO), Mokhtar Belmokhtar's factions, and other militant groups outside Nigeria. In 2014, Nigerian President, Goodluck Jonathan even went so far as calling Boko Harām "al-Qaeda in West Africa". By 2012, attacks by Nigerian Islamist militias on targets beyond Nigeria's borders were still limited, and should not be confused with the activities of other groups (for example, the responsibility of AQIM for most attacks in Niger). Despite this, there were concerns that conflict could spread to Nigeria's neighbours, especially Cameroon, where it existed at a relatively low level until 2014, subsequently escalating considerably. It should also be noted there are combatants from neighboring Chad and Niger. In 2015, Boko Haram swore allegiance to ISIL.
On 17 May 2014, the presidents of Benin, Chad, Cameroon, Nigeria and Niger met for a summit in Paris and agreed to combat Boko Harām on a coordinated basis, sharing in particular surveillance and intelligence gathering. Goodluck Jonathan and Chadian counterpart, Idriss Deby have both declared total war on Boko Harām. Western nations, including Britain, France, Israel, and the United States had also pledged support including technical expertise and training.The New York Times reported in March 2015 that hundreds of private military contractors from South Africa and other countries are playing a decisive role in Nigeria's military campaign, operating attack helicopters and armored personnel carriers and assisting in the planning of operations.
^Following Mohammed Yusuf's death, Boko Haram splintered into numerous factions which no longer operated under a unified leadership. Though Abubakar Shekau eventually became the preeminent commander of the movement, he never really controlled all Boko Haram groups. Instead the factions were loosely allied, but also occasionally clashed with each other. This situation changed in 2015, when Shekau pledged allegiance to ISIL. The leadership of ISIL eventually decided to replace Shekau as local commander with Abu Mus'ab al-Barnawi, whereupon the movement split completely. Shekau no longer recognized the authority of ISIL, and his loyalists started to openly fight the followers of al-Barnawi.
^The exact origin of Ansaru is unclear, but it had already existed as Boko Haram faction before officially announcing its foundation as separate group on 1 January 2012. The group has no known military presence in Nigeria since 2015, but several of its members appear to be still active.
Blench, R. M., Daniel, P. & Hassan, Umaru (2003): Access rights and conflict over common pool resources in three states in Nigeria. Report to Conflict Resolution Unit, World Bank (extracted section on Jos Plateau)