in world war i, the u.s. army used "evacuation hospitals" (called "evacs") which were a part of getting them care as soon as possible. stretcher bearers were medical soldiers who carried the wounded off the field. they were first brought to the battalion aid station. here medics gave basic first aid. for any more serious treatment stretcher bearers and ambulances took the wounded to a field hospital. at the field hospital, they went through triage which was a process of sorting out patients by how serious and life-threatening their wounds were. soldiers who were exposed to poison gas were treated at specially equipped hospitals. after triage, they were taken by ambulance to the evacuation hospitals. there they received surgery and would stay there while they got better. after the evac hospital, they went to base hospitals where they could receive more care and rest. world war i was the first time the army experimented with mobile hospitals.