quired more two-wheeled than four-wheeled ambulances, and even these were in short supply. In 1862 and 1863 scarce ambulances, poorly trained stretcher bearers, and unruly ambulance drivers greatly hindered the Medical Department's efforts to care for the wounded. Ambulances were so scarce that after the first major battle of the war at Bull Run (21 July 1861) many of the 1,000 Union wounded depended on friends and relatives to pick them up in a family carriage. Many more simply straggled the twenty-five miles back to Washington on foot. Three days after the battle hundreds of wounded still lay where they had fallen. The stretcher bearers consisted almost entirely of members of military bands who had been assigned the duty. As one historian noted, "...scrubbing blood-soaked floors and tables, disposing of dirty scabby bandages and carrying bleeding, shell-shocked soldiers had nothing to do with music, accordingly the impressed musicians fled the scene."

At the second battle of Bull Run (29 August 1862) the large number of civilian drifters hired by the Quartermaster Corps to drive the ambulances simply fled the scene at the first few shots. The Surgeon General quickly rounded up about two hundred more vehicles from the streets of Washington and accepted civilian volunteer drivers, who proved to be worse than the first lot. Many broke into the medicine cabinets on the ambulances, drank the liquor supply, then disappeared. Those who made their way to Bull Run were found stealing blankets and other provisions, and some even took to rifling the pockets of the dead and dying.

Over the course of the war, however, the Union system markedly improved, thanks to the efforts of Maj. Jonathan Letterman, Medical Director of the Army of the Potomac. Letterman recommended sweeping reforms in the ambulance system and the creation of an orderly group of medical clearing stations to the immediate rear of each battlefront. The mission of the ambulances was to bring all casualties to the clearing stations as rapidly as possible. The station would then sort the casualties, a process known as triage. As soon as possible the surgeons went to work on the serious casualties whom they deemed savable and sent them to hospitals in the rear. The most seriously wounded were often set aside, many to die before they reached the operating table. The lightly wounded were treated later and retained near the front. Two goals suffused Letterman's new system: to reduce the time between wounding and lifesaving (definitive) surgery, and to evacuate a casualty no farther to the rear than his wounds demanded. This would result in a hierarchy of medical services, a chain of evacuation that carried a patient to more specialized care the farther he moved from the front.

On 2 August 1862 Maj. Gen. George B. McClellan ordered that Letterman's plan be placed into effect in the Army of the Potomac. Ambulances were to be used only for the transport of sick or wounded soldiers. Stretcher-bearers and hospital stewards were to wear distinc-