a field hospital includes full accomodation (tented or prefabricated), ambulances, vehicles, operating theatre, sterilizer, x-ray, dentist, equipment workshop, intensive care unit, examination rooms, mortuary etc; as a standby forces standard component, the field hospital provides second and limited third line medical support to military units: 50 beds, clinical, surgical and dental services, sterilization and lab facilities, ambulance and catering services.  andypandy (src: www.un.org/depts/dpko/glossary) 

A field hospital is a large mobile medical unit near the battle lines.   fabio.iuliano (src: Wikipedia)