Original sentence: The Ballymurphy massacre was a series of incidents between 9 and 11 August 1971, in which the 1st Battalion, Parachute Regiment of the British Army killed ten civilians in Ballymurphy, Belfast, Northern Ireland, as part of Operation Demetrius (internment without trial)
Edited sentence: The Ballymurphy massacre was a series of incidents between 9 and 11 August 1971, in which the 1st Battalion, Parachute Regiment of the British Army killed eleven civilians in Ballymurphy, Belfast, Northern Ireland, as part of Operation Demetrius (internment without trial)