Field hospital A field hospital is a large mobile medical unit that temporarily takes care of casualties on - site before they can be safely transported to more permanent hospital facilities . This term is used overwhelmingly with reference to military situations , but may also be used in times of disaster . The concept was inherited from the battlefield ( such as the Mobile Army Surgical Hospital or MASH ) , and is now applied in case of disasters or major accidents , as well as with traditional Military medicine . A field hospital is a medical staff with a mobile medical kit and , often , a wide tent - like shelter ( at times an inflatable structure in modern usage ) so that it can be readily set up near the source of the casualties . In an urban environment , the field hospital is often established in an easily accessible and highly visible building ( such as a restaurant , school , and so on ) . In case of an airborne structure , the mobile medical kit is often placed in normalized container ; the container itself is then used as shelter . A field hospital is generally larger than a temporary aid station but smaller than a permanent military hospital . In modern laws of war , such as the 1949 Geneva Conventions , include prohibitions on attacking doctors , ambulances , hospital ship s , or field hospitals buildings displaying a Red Cross , a Red Crescent or other emblem related to the International Red Cross and Red Crescent Movement . In the photo at right , some structures bear the Red Cross , while others do not and are fair targets to hostile attack . History . Field hospitals were originally called ambulances . The surgical , evacuation , or field hospitals would remain many miles in the rear , and the divisional clearing stations were never intended to provide emergency life - saving surgery . With the Army ’ s larger mobile hospitals unable to assume their traditional role in support of the front line combat units , the chain of evacuation was interrupted at a critical point . Some sort of interim solution had to be found quickly to provide the necessary surgical services and care to the severely wounded directly behind the front lines . Otherwise , many wounded soldiers would die from either the lack of life - saving surgery at the front or from the long and arduous evacuation trek along jungle trails from the frontal clearing stations to the nearest surgical unit . Manned with skilled surgeons and located close to the fighting to render quick , life - saving surgical intervention , the portable hospital could be moved by its own personnel to remain with the infantrymen during fluid operations . 1900s . A team of Medical Corps officers modified the basic War Department for a standard 25 - bed station hospital into a new theater and table of basic for a portable hospital of 25 - beds . The new unit was capable of supporting small units in its camp - type version ( with 4 female Army nurses and organic vehicles ) or battalion and regimental combat teams in its task force version ( without the 4 nurses and organic vehicles ) . Commanded by a Medical Corps captain or major , the new 29 - man portable hospital had 4 medical officers 3 general surgeons and 25 enlisted men , including 2 surgical and 11 medical technicians . What really marked a radical departure was that all of the unit ' s equipment , medical and surgical supplies , and rations could weigh no more than the 29 men could personally transport . Because the surgical demands on the theater ’ s hospitals were then only minimal , a large number of trained surgeons were available in Australia to man the new units . The surgeons in many of the initial portable hospitals would set standards of excellence in surgery and care that firmly established the reputation of the portable hospitals throughout the theater . However , this was not true of all of the units , and in some instances hospital commanders took advantage of this opportunity to unburden themselves of their unproductive and less well qualified surgeons . Hastily assembled and trained , the portable hospitals suffered from many shortcomings in personnel and equipment , which would soon become obvious in the jungle fighting around Buna . Probably the single most critical problem was the severe limitation placed on the total weight to assure the unit ’ s portability . From the start , this meant that to be portable the unit had to give up medical and surgical equipment and supplies that would have been most useful in the field . Another handicap was the lack of a coherent doctrine for the tactical employment of the portable hospitals , along with an explanation of their exact role in the chain of treatment and evacuation within the combat zone . The Chief Surgeon ’ s Office promulgated a basic doctrine in September 1942 when the portable hospitals were established , but that doctrine went to the base sections in Australia and the portable hospitals and not to the medical units or surgeons in the Advanced Base in Papua and combat units . With no actual operational experience as a basis , that doctrine was much more conjectural than concrete . The Surgeon General ' s Office and the War Department enthusiastically adopted SWPA ' s new hospital as a regular unit before the first portable hospitals proved their value in the Buna campaign . The Surgeon General sought and received approval to add 48 of the new portable hospitals to the War Department ' s troop basis for 1943 . Based on what was learned at Buna . By the end of 1943 , the 48 new units were activated , two of which were assigned to SWPA . Another 15 new units would arrive in the theater during 1944 to support the increasing pace of MacArthur ' s offensive operations along the northern coast of New Guinea and into the Philippines . One portable surgical hospital was now allocated per infantry regiment , 3 per division , although additional hospitals were often authorized in larger operations . During the war , a total of 103 portable surgical hospitals were activated and 78 would serve in various theaters around the world through end of the war — 19 in the China - Burma - India , China , or India - Burma theaters ; 12 in the Pacific Ocean Area ' s South and Central Pacific theaters ; and 51 in SWPA ( 4 moved to SWPA from the South Pacific during 1944 ) . Six PSHs were assigned to the European Theater of Operations , but they arrived only after the end of hostilities . Thus , Carroll ' s temporary innovation gained significance far beyond SWPA , and the life - saving surgical work performed in all of these hospitals during the war saved the lives of many thousands of critically wounded soldiers and airmen . While equipment was always a critical concern , it was the skill level of the surgeons that most concerned the surgical consultants of the Sixth and Eighth U . S . Armies in SWPA . They saw as one of their primary functions the selection of the surgeons for the portable surgical hospitals . As the war dragged on into 1944 , the pool of skilled and experienced surgeons that they could draw on in SWPA shrank as demands rapidly increased for such personnel . Increasingly , the portable surgical hospitals were manned with younger and less skilled surgeons . France . Field hospitals in France are managed by the SAMU ( French emergency medical service . Two types of mobile medical kits ( " poste sanitaire mobile " or PSM ) are used : The PSM are stored in the hospitals where there are samu s and smur s . The PMA is organized in four zones : In case of really massive disaster , it is possible to have several PMA ; the evacuation goes then not directly to a hospital , but to another big field hospital called " medical evacuation centre " ( " centre médical d ' évacuation " , CME ) , to avoid the saturation of the hospitals . In case of a red plan , the PMA is under the responsibility of a physician chosen by the director of medical rescue ( DSM ) , and he is assisted by an firefighter officer chosen by the commander of rescue operation ( COS ) . The firefighter officer has in charge the identification of the living casualties and of the secretaryship . The aim of the PMA is to sort and stabilize the casualties before their evacuation to an hospital . A similar system can be set up as a preventive measure for some very big events ( sport championship , cultural events , concert . . . ) , but managed by first aid associations . It is then called an " associative medical post " ( " poste associatif médicalisé " , PAM ) . ( For smaller events , is simple first aid post , with only volunteer certified first responder s and no medical staff , is set up . ) The Civil defence military units ( " Unité d ' instruction et d ' intervention de la sécurité civile " , UIISC ) have airborne field hospitals . The general system is called DICA ( " détachement d ' intervention de catastrophe aéroporté " , i . e . airborne disaster unit ) , and is specialized in search - and - rescue and in emergency medicine ; it can be enhanced by the Fast civil defence medical unit , called ESCRIM ( " élément de sécurité civile rapide d ' intervention médicale " ) . The ESCRIM is a surgical unit ( " detachement d ' appui chirurgical " ) assisted by a medical assistance unit ( DAMHo , " détachement d ' appui médical et d ' hospitalisation " ) ; the later is specialized in pre - and post - operation care , and allows 48h of hospitalization . The UIISC also has a PMA ( i . e . sort , stabilization and evacuation structure ) when the hospital infrastructure of the country is sufficient .