U.S. American Red Cross Nurses loading patient onto ambulance at Base Hospital No. 1. Base Hospital No. 1 functioned from April 9, 1918, to January 20, 1919, during which time 8,142 surgical and 7,481 medical cases were treated. During this period the unit maintained 12 separate messes and occupied over 20 hotels in which sick and wounded were cared for. The most important volunteer group in America during WWI was the American Red Cross. During WWI more than eighteen thousand Red Cross nurses served with the Army and Navy Nurse Corps. Some of these nurses worked at American base hospitals, at field units, and aboard ships. By the time the war ended in November 1918, the Red Cross had become a major national humanitarian organization.