Armed men entered the Government Girls Secondary School in Chibok, Borno State, at night and took away more than two hundred students who had returned to sit examinations.
A small number of girls escaped by jumping from lorries during the journey into the Sambisa forest. The scale of the abduction and the slow official response drew intense criticism of the security services and of the federal government.
A campaign under the hashtag BringBackOurGirls drew international attention. Some of those taken were released in negotiated exchanges in later years, while others remain unaccounted for.
