Timeline: Boko Haram’s deadly evolution

Boko Haram is an extremist militant group whose name translates as “western education is forbidden”. Active since 2002, it is fighting to carve out an Islamic state from ethnically and religiously divided Nigeria. Their attacks have been small-scale until autumn 2010, when fighters free 700 inmates from a prison in Bauchi and attack a mosque in Maiduguri, frequented by Muslims opposing the insurgent group’s ideology of violence.

The group’s terror campaign escalates. Attacks are intensified on government officials, religious leaders, police officers and students. A series of bombs explode in several towns across Nigeria. The boldest assaults target the UN regional headquarters in Abuja, a beer garden in the northeast city of Maiduguri and several churches near the Niger border during Christmas services, killing dozens.

More than 5,000 civilians flee the southern state of Bayelsa following threats of Boko Haram attacks against Christians there. In the following months, the insurgents carry out a series of coordinated attacks in Kano, Nigeria’s second biggest city, killing nearly 200 people. They detonate bomb-laden cars in market areas and churches. In April Boko Haram release a video calling for a jihad against the UK, the US and Israel, although these countries were not directly targeted.

Boko Haram make its first incursion towards the border with Cameroon. In response, the Cameroonian government fortifies the security of its border with Nigeria. Boko Haram suicide bombers attack newspaper offices in the religiously mixed northern city of Kaduna. In other parts of the country, they detonate explosives in several churches, a bakery and police headquarters. Their tactics change from shootouts and raids to mass-casualty attacks and operations targeting infrastructure.

In February, Boko Haram fighters kill female health workers administering polio vaccines and days later to kill three North Korean doctors, by slitting their throats. In May, 200 heavily armed militants attack the northeastern town of Bama, killing dozens of residents and freeing 100 prisoners. Nigerian president Goodluck Jonathan declares a state of emergency in the northeast, granting the military additional powers of arrest as part of the country’s fight against the insurgents.

The death toll continues to rise as Boko Haram attacks become more frequent and widespread, targeting Christians and Muslims. Insurgents raid a Christian boarding school, burning 30 students as they sleep in a dormitory. They shoot Muslim worshippers in mosques in Borno state, and displace an estimated 4,000 people. In December, they attack an air force base in Maiduguri burning down aircrafts and other equipment.

Boko Haram carry out coordinated attacks in several parts of the country. The fighting spills into Cameroon. Repeated reports of bombings and gun raids come from various towns. The militants attack a theological college in Buni Yadi, slitting students’ throats and burning others alive. In April, the group gets global attention after militants abduct more than 250 school girls in the small town of Chibok. The event sparks international outcry and a Twitter campaign with the hashtag #BringBackOurGirls.

The United Nations designate Boko Haram as an Al-Qaeda affiliate and approves sanctions against the insurgents. The Cameroonian government says the group is recruiting new members from mosques in towns bordering Nigeria. Kidnappings and mass executions continue across the northeast and in the capital, Abuja, and suicide bombers target schools and crowded mosques and markets in northern cities like Kano and Maidguri.

In early January, Boko Haram commit what Amnesty International calls their “deadliest massacre” to date in the northeastern town of Baga. They control all three international borders of the Borno state, making spill overs more likely. Chad and the African Union respond by sending troops to Nigeria, and a major new offensive by the Nigerian army in early March reclaims significant territory. Boko Haram pledges allegiance to Isis but continues to lose territory it controlled in Nigeria’s northeast.