In Article 7 of the first Geneva Convention of 1864, the red cross on a white background was defined as the symbol that would identify the people and institutions that were under its protection. In 1929, the red crescent was adopted as an additional sign of protection.
The Logos of the International Red Cross and Red Crescent Movement at the Entrance to the Museum of the Red Cross and Red Crescent in Geneva, colour photograph, 2005, photographer: Julius.kusuma; source: Wikimedia Commons, attribution – reproduction permitted under the same conditions 3.0 Unported (CC BY-SA 3.0).