During the first world-war there was a great need for large buildings to be used as auxiliary hospitals for the wounded returning from France. Mapperley Hall was offered to the St Johns Ambulance who took over the building. It was converted into a 40 bed hospital as the Mapperley Hall Auxiliary Hospital opening for arriving wounded 1916. The Commandant and driving force of the hospital was Lady Cecily Mary Cavendish-Bentinck who ran it successfully throughout the war. She was the wife of Lt Col Lord Charles Cavendish-Bentinck who was the Deputy Lieutenant of Nottinghamshire and fought in France during world war one.