Aid Posts were situated in or close behind the Front Line. The Units in the trenches provided these posts and generally had a medical officer, orderlies and men trained as Stretcher Bearers. The Field Ambulance 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 personnel involved were well within the zone where they could be under fire.
As well as the Bearer Posts, the Field Ambulance established Main and Advanced i.e. forward Dressing Stations where a casualty could receive further treatment and his condition be stabilised in preparation for evacuation to a Casualty Clearing Station. Men who were ill or injured would also be sent to the Dressing Station and in many cases returned to their Unit after first aid or some primary care. Dressing Stations were set up in existing buildings, bunkers and dug-outs, anywhere there was some protection from enemy shell fire and aerial attack. These Dressing Stations were generally manned by Field Ambulance personnel.
Once treated casualties were moved rearwards several miles to the Casualty Clearing Centre. This may be on foot, by horse-drawn wagon, motor ambulance or lorry or, in some cases, by light railway. At this point the casualty left the care of the Field Ambulance and, depending on their medical condition, would receive further treatment in hospitals set up behind the front lines or may even be sent to Britain.