Following is a timeline of events since the Boko Haram abducted more than 200 schoolgirls from the northeastern Nigerian town of Chibok in 2014.

Snatched from school

On April 14, 2014, Boko Haram gunmen seize more than 276 girls from the Government Girls Secondary School in Chibok, Borno State. The girls are forced from their dormitories onto trucks and driven into the bush. Fifty seven girls manage to flee.

Boko Haram leader Abubakar Shekau claims responsibility in a video released on May 5, 2014, and vows to sell the girls as slave brides. A week later, a second video shows about 100 of the missing girls. Boko Haram says they have converted to Islam and will not be released unless militant fighters held in custody are freed.

Global response

An international media campaign is launched, backed by U.S. First Lady Michelle Obama and Nobel Peace Prize laureate Malala Yousafzai. The hashtag #BringBackOurGirls fires up a social media storm.

On May 17, 2014, Benin, Cameroon, Chad, Niger and Nigeria vow to fight Boko Haram together, in what Cameroon President Paul Biya terms a “declaration of war”.

The U.N. Security Council says the kidnappings “may amount to crimes against humanity”, as Britain, China, France, Israel and the U.S. offer help.

U.S. military specialists deploy to neighbouring Chad but later move elsewhere after Nigeria stops requesting their services.

On May 26, 2014, Nigeria’s Chief of Defence Staff Alex Badeh says the girls have been located but warns a rescue operation would put their lives at risk.

On April 14, 2015, Nigeria’s President-elect Muhammadu Buhari warns he “cannot promise that we can find” the girls, as vigils are held in many countries to mark their first year in captivity.

Amnesty International says the girls may have been separated into three or four groups and are being held in camps, some of which might be in Cameroon or Chad.

Mr. Buhari says in late December 2015 he is willing to negotiate with any “credible” Boko Haram leadership, a week after claiming the country has “technically” won the war against Boko Haram.

Other victims freed

Throughout 2015, the Nigerian military announces the rescue of hundreds of people, most of them women and children, who have been kidnapped by Boko Haram.

But the missing schoolgirls are not among them, despite several unconfirmed sightings.

Suicide attacks using women and young girls increase against “soft” civilian targets such as mosques, markets and bus stations, fuelling fears that Boko Haram might be using its captives as human bombs.

In March 2016, it emerges that Boko Haram also seized 500 women and children from the north east town of Damasak in Borno State just months after the Chibok abduction. The kidnapping was denied at the time.

‘Proof of life’

On the eve of the abduction’s second anniversary, U.S. news channel CNN reports that Boko Haram has sent a “proof of life” video which shows 15 of the girls — the first concrete indication that at least some are still alive.

On May 18, 2016, the Nigerian Army confirms the first of the schoolgirls has been found. The 19-year-old, who later meets President Buhari, was discovered with a four-month-old baby and a man she described as her husband near Boko Haram’s Sambisa Forest enclave.

Prisoner exchange

This October 19, 2016 ohoto shows 21 Chibok girls who were released by Boko Haram a week before, attending a meeting with the Nigerian President at the State House in Abuja, Nigeria. | Photo Credit: AFP

On October 13, 2016, Nigerian officials announce the release of 21 of the girls following talks between the government and Boko Haram brokered by Switzerland and the International Red Cross.

Local sources say four jihadist prisoners were freed as part of the deal to secure the girls’ release.

The Nigerian government raises the prospect that more releases could follow, with a senior official in the president’s office saying that “the negotiations will continue”.

82 released in prisoner swap

On May 6, 2017, Nigeria says it has negotiated the release of 82 of the girls, securing their freedom in a prisoner swap deal.