Larrey initiated the modern method of army surgery, field hospitals and the system of army ambulance corps. After seeing the speed with which the carriages of the French flying artillery maneuvered across the battlefields, Larrey adapted them as ambulance volantes ("Flying ambulances") for rapid transport of the wounded and manned them with trained crews of drivers, corpsmen and litterbearers. At the Battle of Metz (1793) Larrey successfully demonstrated the value of field ambulances. The quartermaster-general Jacques-Pierre Orillard de Villemanzy ordered prototypes to be built, after which ambulances would be supplied to all the Republic's armies. Larrey also increased the mobility and improved the organization of field hospitals, effectively creating a forerunner of the modern MASH units. He established a rule for the triage of war casualties, treating the wounded according to the seriousness of their injuries and urgency of need for medical care, regardless of their rank or nationality. Soldiers of enemy armies, as well as those of the French and their allies, were treated.
Larrey's writings are still regarded as valuable sources of surgical and medical knowledge and have been translated into all modern languages.