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Main function: Casualty Clearing Stations were the pivot point in which the whole system of evacuation turned from collecting casualties to distributing them.  Casualties were received, assessed, then divided into three categories (known today as triage). These categories were: 

  1. Non-serious cases - to be returned to duty after recuperation and rest. 

  2. Serious cases but still fit to travel - to be immediately evacuated back to the base hospitals. 

  3. Serious cases in urgent need of immediate treatment. 


Casualties were provided with food and rest, and were prepared for their further journey, which could have been immediate or after recuperation. The main objective was to provide necessary treatment and move patients out as quickly as possible. However, as a result of their evolution and expansion, it became possible for recuperating patients to be retained for up to four weeks before being returned to their units or transferred to a General Hospital via Ambulance Trains or Inland Water Transport (barge).


The discussion of CCSs is difficult to generalize because they were the one link in the evacuation chain that radically evolved over the course of the war. The CCS of 1914 was not the CCS of 1918.

1914 and 1915: CCSs mobilized in August 1914 under the title 'Clearing Hospitals'. During the 1914 retreat, the equipment of most of the Clearing Hospitals was still in transit, consequently, they did not start to become fully effective units until early 1915. By this time it had become obvious to the medical services that there was public and professional confusion about the CCS's role. Was it a sorting centre or a hospital as it's title suggested? This resulted in their official title being changed to 'Casualty Clearing Station'. In spite of the name change, very high volumes of urgent cases, (i.e, gas gangrene or abdominal injuries) arrived at the CCSs at an alarming rate. Unequipped to deal with this influx, in early 1915, the Director General of Medical Services (D.G.M.S.) approved the increase of surgical work and appropriated extra surgical equipment to be moved forward from the hospitals to the CCSs. By the middle of 1915 it became standard practice for head injuries, compound fractures, and penetrating wounds of the limb to be sent straight to CCSs.

1916: Despite surgery now taking place in CCSs, surgeons began arguing that facilities were required to enable surgery to take place even closer to the Front lines, to prevent a potentially fatal delay in the treatment of infected wounds. Post mortems of abdominal cases had revealed that most had died of hemorrhaging, which might have been avoided by earlier surgery. It was argued that Field Ambulances were not able to provide such facilities because of post-operative care - it was not advisable to move patients immediately after an operation and Field Ambulances were frequently on the move. Also, they were not in a position to provide patients with comfortable beds or nursing care, thus hindering a patients' recuperation time, Arrangements for sterilizing instruments and gowns etc were also more difficult at Field Ambulances. All evidence indicated that the success rate for abdominal surgery was much higher when performed at CCSs rather than Field Ambulances, so all in all it was decided to bring CCSs in as close as 10,000 yards from the Front lines as opposed to roughly 20 kilometers away. This, however, resulted in them now coming under enemy attack, especially from aircraft bombing.

Their positioning at railheads meant that CCSs were now becoming static and, despite the name change, were becoming more like hospitals. In some areas though, it was impossible to bring a CCS very close due to unfavourable topography. This resulted in the formation of Advanced Operating Centres and Abdominal Hospitals. (see 'Formation' section) 


1917: By 1917, more operations were performed at CCSs than base hospitals. From 24th July 1917, the distribution of sick and wounded to CCSs was regulated in accordance of the D.M.S. of the Fifth Army to treat certain types of wounds. The Field Ambulances became the sorting centres, separating, for example head wounds from stomach wounds at the ADSs, and transporting them to the relevant CCS. Specific CCSs were also allocated to treat self-inflicted wounds, as well as infectious cases, and those who were gassed. Other measures established at CCSs in 1917 were surgical cleaning of wounds before evacuation to the base, the principle of retaining so-called shell shock cases, and measures to deal with mustard gas, which was used by the enemy for the time in 1917. Also by 1917 nursing sisters were successfully trained in the administration of anaesthetics, which was successful and freed up more than a hundred medical officers for other duties.

1918: The spring 1918 German offensive placed the CCSs in danger of becoming part of front line action, which caused them to become mobile again and retreat. By June 1918 they had reduced in size, and many had lost their equipment to the enemy - some sent by transport to a different location, and some taken by the enemy. They were no longer situated on railheads or in other areas designed to promote easy evacuation of the wounded because they had been on the move. By the time of the Allied Counter-Offensive in August, they had recovered their losses, but it was agreed, that although they would be placed as far forward as possible, they must remain sufficiently mobile to keep up pace with any advance or retreat.

Stretcher cases awaiting transport to a Casualty Clearing Station lie on the ground outside a dressing station at Blangy, during the Battle of Arras in April 1917. 
Image courtesy of IWM.


In normal circumstances CCS personnel would included 8 Medical Officers (The C/O, 6 doctors, and 1 surgical specialist), 1 Quartermaster, 7 QAIMNS, and 77 other ranks (working as clerks, cooks, nursing orderlies, theatre orderlies, stretcher-bearers etc.) Often a dentist and a pathologist were attached. Non-medical personnel attached would include 3 chaplains, 4 lorry drivers, 2 Royal Engineers personnel - an electrician and engine hand, and men from the Army Service Corps, employed as ambulance drivers.

This small staff was sufficient in quiet times but totally inadequate during battle. In times of heavy fighting, the number of personnel could be increased and specialized by bringing 'Surgical Teams' forward. A surgical team was made up of a surgeon, an anaesthetist, a theatre sister, 2 theatre orderlies, 4 stretcher bearers, and a batman. The extra personnel were brought in from hospitals at the base, or from CCSs and/or Field Ambulances which were not engaged in active operations. Additional nursing sisters were also attached in proportion from 7 to 24 or more.

Image courtesy of IWM

In September 1916, every CCS was divided into a heavy and a light section. The light section was designed to be able to move forward or retire in line with the troops at a moment's notice. A light section was also used to set up Advanced Operating Centres or Abdominal Hospitals. 

CCSs usually worked in groups of twos or threes, and in relay. This meant one would be closed and treating casualties for evacuation by train or ambulance to the Base Area, whilst the other would be empty and readying itself to receive new casualties. When the second one became full it would close, but the first would by now be empty and ready to receive new casualties again. A third would only be treating the sick, but would evacuate to receive battle casualties in an emergency. Each CCS took around 150 to 200 wounded before they closed and new patients arriving were redirected to another CCS.

Early CCSs were established in buildings, but with the need for expansion, they began setting up on open ground, using tents and hospital Nissen huts. When on open ground they were situated near a railway siding for their own use, with a good road and communication towards the Front. The tents and huts provided accommodation for staff, and wounded, as well as operating theatres, medical and surgical stores, kitchens, sanitation, incineration plant, ablutions, and a mortuary. Portable generators were supplied to provide lighting. 

The conditions which determined the selection of sites for CCSs were: proximity to railways, good road approaches, reasonable security from hostile artillery fire, and adequate water supply.

Capacity: Early CCSs were set up to provide accommodation for 200 patients, however the number of surgical operations being performed by 1917 meant they had expanded greatly, and were able to receive between 800 - 1,200 sick and wounded.


The standard system of receiving and treating casualties arriving at a CCS meant patients would go through:

  • The stretcher exchange dump - where the drivers of motor ambulances delivered casualties and exchanged the equivalent of equipment handed in. 

  • A general admission tent or hut, or a receiving section - where a patient's particulars were recorded in an Admission and Discharge (A & D) book, and his medical condition was classified by a medical officer. Refreshments such as tea, coffee, hot soup, sandwiches, and cigarettes were supplied here for waiting patients.

A patient might then go to:

  • A section for the dressing of walking patients: Here a patient might sit on benches, where he was attended to by a sister and/or orderlies working under a medical officer.

  • A section for the dressing of lying down patients: Stretcher cases were carried here. If the patient's wound was slight, it would be dressed, and the patient was then taken to the evacuation ward. If his wounds were more serious he was passed on to the pre-operation ward.

  • A pre-operation section: Here the patient's clothes were cut away, and he was cleansed, warmed and fed.

  • A resuscitation ward: If on arrival the patient's condition was too unstable for surgery, he was taken to the resuscitation ward, where a medical officer, a sister, and orderlies attended to his revivification. He was rested, warmed, infused or transfused - whichever might have been necessary. 

  • X-ray department: There were six mobile X-Ray units serving in the British Expeditionary Force during the Great War and these were sent to assist the CCS's during the great battles.

  • Operating theatre: After 1916 there could be one or two theatres accommodating up to 12 tables arranged in pairs, each pair being divided from the other to provide privacy. Two tables were often provided for each team in order to save time. Surgical teams often worked in groups of 3 for 8 hours shifts with 4 hours off to sleep. This pattern could enable two operating tables to run continuously for a week. In reality, different CCSs worked in different ways. 

  • Evacuation Section: After an operation, the patient could be carried here to await evacuation back to a Base Hospital. As stated above, slightly wounded were sent here after their wounds were dressed.

  • Retention ward: If the patient was too ill to be evacuated, he was taken to a retention ward. These were situated at the back of the CCS in as quiet a place as possible. He was attended to here by the nurses and medical officers.


View of 3rd Australian CCS at Grevillers

Image courtesy of AWM


Equipment: In 1914, there were no definite regulations limiting the amount of material and tentage which could be added to CCSs. Individual commanding officers requisitioned for whatever equipment they might consider necessary. However, it was recommended that every CCS have tents to accommodate 200 patients, 210 stretchers, 200 Paillasse cases, 200 bolster cases, 480 sheets, 50 feather pillows, 400 blankets, along with sufficient cooking and feeding utensils, medical stores and comforts, and surgical equipment. Surgical equipment comprised of: 1 small operating tent, 1 operating table, a few wooden splints, and a few yards of aluminum splinting. Doctors were encouraged to use local resources to obtain what they required. In June 1915, a further increase of equipment was authorized and CCSs were supplied with the 'Bowlby Outfit No 2'. Later in the war small operating tents/areas were replaced by a Nissan hut of 60 feet in length and 20 feet in width - room for 4 operating tables and their equipment.


Due to the vast expansion of CCSs, it became necessary to regulate the quantity of equipment allocated. The new scale equipment was issued in routine orders. Sets of equipment were kept in reserve at the Base Depot of Medical Stores in Boulogne and was sent up when required. This equipment list is far too large to state here but can be found in Volume II of the Medical Services General Official History and Volume I of the Medical Services Surgery of the War.


Transport: There was no scale for transport laid down for the units in 1914 mobilization tables, but a footnote explained that if transport was required it would be furnished under the orders of the Inspector-General of communications. It was advised they should receive 17 general service wagons and 8 or 9 3-ton motor lorries when the unit was on the move. However, after they had expanded it was documented that as many as 100, or even in one case 200, lorry loads or a complete train of goods vans had been used.

Ambulance Trains and Barges

Casualties would normally be moved from the CCS to a Base Hospital,by specially-fitted ambulance train or in some circumstances by barge along a canal.

Read more in the next section: Base Hospital

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