A British museum is to repatriate two locks of hair taken from the corpse of an Ethiopian emperor during one of the most colourful military campaigns of the Victorian era.

Monday’s decision by the National Army Museum in Chelsea marks the latest breakthrough in Ethiopia’s long campaign to reclaim hundreds of artefacts seized during Sir Robert Napier’s punitive expedition to Abyssinia in 1868.

The museum said it had agreed to an Ethiopian government request made last year to return the hair of Theodore II, who shot himself with a duelling pistol given to him by Queen Victoria rather than be captured by Napier’s forces.

“Having spent considerable time researching the provenance and cultural sensitivities around this matter, we believe the Ethiopian government claim to repatriate is reasonable,” Terri Dendy, a senior museum curator, said.

The Ethiopian government welcomed the return of the braids, a move it hopes will precede the return of hundreds of other artefacts from the “Magdala Treasures” held in a dozen libraries and museums across Britain.

Last year, Tristram Hunt, director of the Victoria and Albert, raised the possibility of sending some of the museum’s Magdala artefacts, including the emperor’s gold crown and chalice, to Ethiopia on a long-term loan.