The evacuation chain for wounded and sick soldiers

This page describes the main medical functions in a complex chain that processed the casualty from the front line back to hospitals at home. It is in a simplified format. Many men missed stages altogether, and of course many wounded soldiers were in no condition to know which of these units was caring for them.

Aid and Bearer Relay Posts

The casualty is likely to have received first medical attention at aid posts situated in or close behind the front line position. Units in the trenches provided such posts and generally had a Medical Officer, orderlies and men trained as stretcher bearers who would provide this support. The Field Ambulance (see below) would provide relays of stretcher bearers and men skilled in first aid, at a series of “bearer posts” along the route of evacuation from the trenches. All involved were well within the zone where they could be under fire.


Stretcher-bearers carrying an injured man on a stretcher down a twisting trench in Salonika. Imperial War Museum copyright image Q31794. Note also the walking wounded following them. These men have clearly already received some rudimentary medical assistance in the trenches.

Field Ambulance

This was a mobile medical unit, not a vehicle. Each British division had three such units, as well as a specialist medical sanitary unit. The Field Ambulances provided the bearer posts but also estabished Main and Advanced (that is, forward) Dressing Stations where a casualty could receive further treatment and be got into a condition where he could be evacuated to a Casualty Clearing Station. Men who were ill or injured would also be sent to the Dressing Stations and in many cases returned to their unit after first aid or some primary care.


This diagram from a Canadian history shows the locations and types of aid posts and dressing stations that supported the 1st Canadian Division during the opening of the Second Battle of Ypres. There are six regimental aid posts behind the front line, two Advanced and two Main Dressing Stations.

There was no hard and fast rule regarding the location of a Dressing Station: existing buildings and underground dug-outs and bunkers were most common, simply because they afforded some protection from enemy shell fire and aerial attack. The Dressing Stations were generally manned by the Field Ambulances of the Royal Army Medical Corps.


An Australian Medical Officer attends a wounded man at an Advanced Dressing Station during the Third Battle of Ypres in 1917. Imperial War Museum copyright image E(AUS)714.

Once treated at a Dressing Station, casualties would be moved rearward several miles to the Casualty Clearing Station. This might be on foot; or on a horse drawn wagon or motor ambulance or lorry; or in some cases by light railway. It is helpful to consult the war diary of the Assistant Director of Medical Services of the Division relevant to the man’s unit, for they usually have very detailed reports on the locations of the bearer and dressing stations at the time that the man was being evacuated.


A Field Ambulance wagon passing over muddy ground near Ovillers, Somme, in September 1916. Imperial War Museum copyright image Q1098. This may be on its way from a Dressing Station to a Casualty Clearing Station. Imagine what wounded men suffered when moving over such ground on this type of transport.

The next three images are from the war diary of 76 Field Ambulance, a unit under command of 25th Division, and relate to its time in the Ypres area during the Third Battle of Ypres offensive in August 1917. The diary reference is WO95/2239 and the images are Crown Copyright.


Click on the image for a full scale view. Note the bearer posts and relay stations linking back from the units at the front to a Dressing Station at (or perhaps more accurately, given this sketch, near) the ruined site of Hooge Chateau.


Click on the image for a full scale view. This is a circuit for horse drawn ambulance transport, picking up casualties at the Hooge Chateau Advanced Dressing Station (in square 15) and taking them out of the battlfield past Dickebusch. A typical onward route from there would be to the group of CCSs at Remy Farm (Lijssenthoek).


The Hooge Chateau Advanced Dressing Station dealt with 3395 casualties in the period 1 to 14 August 1917, of which just under 1000 were on 10-11 August alone. About a third were stretecher cases and the rest were able to move, to some extent, on their own. These figures and proportions were not untypical for a unit involved in a major action.


Wounded British troops arriving at 43 Casualty Clearing Station, Frevent, 8 April 1918. Imperial War Museum copyright image Q334.

Casualty Clearing Station

Until 9 January 1915 these units were known as Clearing Hospitals.

The CCS was the first large, well-equipped and static medical facility that the wounded man would visit. Its role was to retain all serious cases that were unfit for further travel; to treat and return slight cases to their unit; and evacuate all others to Base Hospitals. It was often a tented camp, although when possible the accommodation would be in huts. CCS’s were often grouped into clusters of two or three in a small area, usually a few miles behind the lines and on a railway line. A typical CCS could hold 1,000 casualties at any time, and each would admit 15-300 cases, in rotation. At peak times of battle, even the CCS’s were overflowing. Serious operations such as limb amputations were carried out here. Some CCS’s were specialist unit, for nervous disorders, skin diseases, infectious diseases, certain types of wounds, etc. CCS’s did not move location very often, and the transport infrastructure of railways usually dictated their location. Most evacuated casualties came away from the CCS by rail, although motor ambulances and canal barges also carried casualties to Base Hospitals, or directly to a port of embarkation if the man had been identified as a “Blighty” case. (In 1916, 734,000 wounded men were evacuated from CCS’s by train and another 17,000 by barge, on the Western Front alone. There were 4 ambulance trains in 1914 and 28 by July 1916). The serious nature of many wounds defied the medical facilities and skills of a CCS, and many CCS positions are today marked by large military cemeteries. CCS’s also catered for sick men. Generally, considering the conditions, the troops were kept in good health. Great care was taken in reporting sickness and infection, and early preventive measures were taken. The largest percentage of sick men were venereal disease cases at 18.1 per 1000 casualties; trench foot was next with 12.7. Until mid 1915, the CCS was known as a Clearing Hospital. Generally there was one provided for each Division. From the CCS, the casualty would be evacuated to a Base Hospital.

A wonderful sketch plan of 3 CCS located at Grévillers on 31 May 1917. From its war diary. Crown Copyright.


A ward of the 2nd Australian Casualty Clearing Station at Steenwerke, November 1917. Imperial War Museum copyright image E(AUS)4293.

The locations of the CCS’s in France, Belgium and (later) Germany


This map of May 1918 gives an impression of the great extent of the CCS’s established at Remy Farm, Lijssenthoek, in the rear areas of the Ypres sector. The blue rectangles are huts and buildings of the CCS’s. Note the railway line passing through the camp. The inevitable cemetery at Remy Farm became one of the largest on the Western Front and now has an interpretive visitor centre next door – well worth seeing for an understanding of how a CCS functioned.


Wounded British troops outside a Casualty Clearing Station at Heilly, Somme, September 1916. Imperial War Museum copyright image Q1255. Note the train in the distance, left. These men are likely to be waiting for a move to a Base Hospital.

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.

Ambulance Train evacuations from the Battle of the Somme

Ambulance barges in France and Flanders

Base Hospital

Once admitted to a Base Hospital, the soldier stood a reasonable chance of survival. More than half were evacuated from a General or Stationary Hospital for further treatment or convalescence in the United Kingdom. The Stationary Hospitals, two per Division, could hold 400 casualties each. The General Hospital could hold 1040 patients. They were located near the army’s principal bases at Boulogne, Le Havre, Rouen, Le Touquet and Etaples. The establishment of a General Hospital included 32 Medical Officers of the RAMC, 3 Chaplains, 73 female Nurses and 206 RAMC troops acting as orderlies, etc. The hospitals were enlarged in 1917, to as many as 2,500 beds.

The locations of the Base Hospitals in France

Convalescent Depots

Those casualties who could be returned to duty after treatment at hospital would normally be sent to a Convalescent Depot before being returned to a Base Depot for redeployment.

The Convalescent Depots in France

Home hospital

Existing military hospitals were expanded; many civilian hospitals were turned over in full or part to military use; many auxiliary units opened in large houses or public buildings; and many private hospitals also operated.

The locations of the many of the principal hospitals at home

Transfers to Military Convalescent Hospitals

Command Depot

Once discharged from hospital men were sent to various locations for convalsecence, depending on their circumstances. Many went to the military Command Depots:

List of the Command Depots


The Salonika evacuation chain

Italy casualty evacuation chain

A soldier’s life

Classification of wounds