They were sleeping in their dormitory at Chibok Girls’ Secondary School, with many having come from distant villages to take exams.
Then Boko Haram struck. Altogether 276 girls were kidnapped.
The Islamist militant group had terrorised the north-eastern corner of Nigeria since a wave of attacks in 2009.
They had kidnapped many girls and women before in a conflict that hadn’t garnered significant worldwide attention, but this time was different.
A massive social-media driven campaign followed under the hashtag #BringBackOurGirls. Michelle Obama was among the slew of famous people who endorsed it.
But what happened to the girls?
In the confusion immediately after the kidnapping, 57 managed to escape, but the rest were driven far into the Sambisa forest.
For more than three years the captured girls moved from forest, to city, to caves – shuttled surreptitiously around north-eastern Nigeria.
According to one source, there was plenty of food to begin with – even meat from stolen cows. Boko Haram controlled vast swathes of land and pillaged towns at will.
But 18 months on and with elections looming, the government began taking the war seriously. The army was properly supplied for the first time and made fast gains.
That put pressure on Boko Haram but it also made life harder for their captives - sometimes the girls did not even get one meal a day.
Eventually things improved. The international attention had made them valuable assets – to be traded – and the kidnappers knew it. In the propaganda war, delivering hostages well-fed and healthy would be a show of strength.