Introduction

By two o'clock on September 18, 1862, ambulances had removed the wounded from the right wing of the Army of the Potomac near Antietam Creek. The left took the rest of the day. Those times came from Major Jonathan Letterman, the army's medical director, and they have helped make Antietam an early triumph in the history of organized battlefield evacuation. Letterman's own report described a less uniform achievement. The Second Corps had trained men and an officer directing its ambulances; much of the left wing had no ambulance organization at all, leaving medical officers there to find wagons and attendants as they could.1

Those results came from an army partway through a reform. Six weeks earlier, Letterman had issued an order that placed ambulance crews, vehicles, and horses within a single chain of command. Campaigning began before all of the Army of the Potomac could put that order into practice; the rapid movement into Maryland scattered supplies and brought newly attached formations under medical arrangements they had never learned. Antietam showed that dedicated ambulance crews could clear a large battlefield. It also showed Letterman where evacuation ended and the wider work of caring for thousands of wounded began.

When an Ambulance Belonged to Everyone

Letterman inherited the medical direction of the Army of the Potomac on July 4, soon after the Seven Days' Battles. The retreat to Harrison's Landing had left sick and wounded men along the roads, while exhausted regimental surgeons worked with depleted stores. Ambulances were present, yet their ownership and purpose shifted from place to place. Some belonged to the medical department and others to the quartermaster. Officers used them as personal transportation; quartermasters sometimes loaded them with supplies. When a battle began, the surgeon responsible for removing wounded men could discover that neither wagon nor driver was available.2

The drivers supplied another weakness. Many were temporary details who had received no drill for work under fire and expected to return to their regiments. Civilian teamsters might refuse the field altogether. A surgeon could order a wounded man carried to the rear, but he did not command the driver, the stretcher bearers, the ambulance, or the horses needed to move him. Letterman later recalled vehicles wandering without direction and wounded soldiers walking because wagons intended for them were carrying baggage. The difficulty began before anyone lifted a stretcher: no officer could be held responsible for the whole journey.3

Second Manassas enlarged the same problem in late August. Major General John Pope's Army of Virginia had not adopted Letterman's new arrangements, and its ambulance drivers lacked the training then beginning in the Army of the Potomac. Thousands of wounded remained on the field during the Union withdrawal. Defeat, confused roads, and the enemy's presence all obstructed their removal, so no administrative reform could have produced an orderly evacuation by itself. The old division of authority made a bad retreat worse.4

Order No. 147

Special Orders No. 147, issued on August 2, attacked that division directly. An ambulance commander at army-corps level supervised officers assigned to divisions and brigades. Each regiment furnished two men and a driver for every ambulance. The attendants trained with stretchers, learned how to place wounded men in the wagons, filled water containers before a march, and reported anyone who used an ambulance without authority. Commissioned line officers supplied military command, but medical officers determined where the wounded would be collected and treated.5

Vehicles and animals became part of the organization as well. Brigade officers inspected the wagons and reported damaged equipment, while the horses could not be taken for other duties and the ambulances moved together in a prescribed place during a march. Green bands on caps and sleeves identified the men authorized to control them. An officer who loaded baggage into an ambulance could be reported, ordered to remove it, and eventually arrested for disobedience.6

Paper traveled more slowly than the army. Letterman wrote that the printed order reached him only a short time before the troops left Harrison's Landing, too late to enforce every detail. He had secured General George B. McClellan's approval, but Secretary of War Edwin Stanton and General in Chief Henry Halleck rejected a proposal to extend the corps beyond McClellan's command. Pope's formations therefore arrived with their own practices when the two armies were combined. The order described positions, duties, inspections, and signals, but filling those positions took longer.7

A System Scattered on the Road

During August the Army of the Potomac moved by water from the James River, through Alexandria, and into the campaign already unfolding in northern Virginia. Orders to embark came so quickly that hospitals, medicines, wagons, and ambulances were left behind at Fortress Monroe and other points. Some of the ambulances sent after the troops were lost in a storm on Chesapeake Bay. Two hundred more issued to the army shortly before Antietam helped replace the missing vehicles, although there was no time to organize them under the August order. Some corps entered Maryland with practiced crews; others brought only wagons.8

Supplies followed the same broken route. After the army crossed the Potomac, Letterman ordered medicines, dressings, hospital stores, bedding, and food forward from Washington. Confederate troops had destroyed the railroad bridge over the Monocacy River, forcing the trains to stop short of Frederick. Hospital wagons from Alexandria carried enough medicines and dressings for surgeons to begin work when the battle opened; afterward, ambulances brought more from Frederick because no wagons could be found. Of twelve wagons Letterman requested for medicines and food, he obtained two at headquarters and loaded them with coffee, sugar, and bread.9

The ground awaiting them ran for roughly six or seven miles. Medical officers chose houses and barns behind the lines as division hospitals, close enough for ambulances to reach but removed from direct fire when the terrain allowed it. No single hospital could absorb the day. Surgeons, stewards, volunteer nurses, local families, and the arriving ambulance crews worked through buildings never designed for thousands of casualties.10

September 17 and 18

Fighting opened before dawn on September 17 and moved across the northern fields in repeated attacks. The front bent through the Cornfield, the West Woods, and the Sunken Road before Major General Ambrose Burnside's troops fought across the creek on the Union left. Every shift changed the path between a wounded man and a dressing station. Men who had fallen behind one line could lie between two after the next advance or retreat. Letterman acknowledged that some could not be reached until the firing had moved away.11

Where the August organization existed, it gave that movement a direction. Captain J. M. Garland commanded the Second Corps ambulance corps and had more vehicles in usable condition than many neighboring formations. His officers could keep crews together, direct them toward collection points, and return loaded wagons to the hospitals. Letterman singled out Garland in both his official report and later memoir. On the right, the last accessible wounded were gathered by early afternoon on September 18.12

The left worked differently. No ambulance corps had been organized there, according to Letterman, and its medical officers assembled whatever help the emergency offered. The work continued until evening, still a rapid clearance compared with earlier battles. On parts of the field, trained ambulance crews followed the August order; elsewhere, improvised labor performed the same work because the printed order had not yet become an organization.13

Two Accounts of the Same Evacuation

Letterman's numbers require the same care as his times. His incomplete returns listed 8,350 Union wounded, while the Center of Military History's modern campaign account estimates about 9,500 wounded and 12,400 Union casualties overall. Approximately 22,720 men in both armies were killed, wounded, or missing after twelve hours of fighting. The official medical report did not count every person who passed through a hospital, and a statement that the field was cleared says little about the treatment each man received afterward.14

The critics preserved in Mary Gillett's history of the Army Medical Department were severe. They complained that ambulance drivers demanded money and stole from the dead and wounded. Some wounded men remained on the field as long as twenty-four hours. Certain failures occurred among Pope's untrained units; others may have involved formations that were supposed to have adopted the new order. The surviving evidence cannot assign every delay to a particular corps. A wounded soldier's experience varied with his location, the hour, the movement of the battle, and the organization that reached him.15

Letterman conceded that men were overlooked and that the system remained imperfect, even as he described the evacuation as better than anything the army had previously accomplished on such a field. The ambulance corps shortened and regularized part of the journey from the firing line. Behind it, hospitals still struggled with food, bedding, shelter, attendants, and the sudden concentration of patients.

What Antietam Taught Letterman

The next orders followed the shortages. On October 4, Letterman reorganized medical supply so that a wagon assigned to each brigade carried a standard stock and remained under medical control. Its contents could be inspected before a march and replenished without waiting for a distant depot. The medicine chest now moved with its regiment, and the larger stock remained with the brigade wagon.16

A second order, issued on October 30, organized division field hospitals. Surgeons were selected for operating, dressing wounds, keeping records, and managing the site; other medical officers returned to regimental care. Ambulance officers now knew where to deliver patients, and hospital staffs could prepare for the divisions they served. At Antietam, houses and barns had become hospitals through necessity. Letterman issued the new assignments on October 30, five weeks before the army marched to Fredericksburg.17

Letterman later identified Fredericksburg, in December 1862, as the first occasion when the completed ambulance system was put into operation and severely tested. Between Maryland and that December battle stood the two October orders, along with weeks spent equipping and instructing the army. Congress extended a formal ambulance corps to all Union armies in March 1864.18

Conclusion

Antietam deserves a place in the history of battlefield evacuation because a new command structure proved useful before it was complete. Dedicated officers and crews gave wounded men on parts of the field a more dependable route to treatment. Elsewhere, the old uncertainty survived: wagons arrived without an organization, supplies stopped at a broken bridge, and medical officers found their own attendants. The differences were visible before the wounded had all left the field on September 18.

Letterman's achievement lay in treating those differences as administrative problems that could be assigned, inspected, and revised. After Antietam he standardized supply wagons and built division hospitals into the system; at Fredericksburg the parts would operate together. The August order had begun with a line of responsibility on paper. In Maryland, Garland's organized crews and the left wing's improvising surgeons showed Letterman what that line could do, and exactly where it still broke.

Endnotes

  1. Jonathan Letterman, Medical Recollections of the Army of the Potomac (New York: D. Appleton, 1866), 42–46, digitized edition; Jonathan Letterman, report dated March 1, 1863, in The War of the Rebellion: A Compilation of the Official Records of the Union and Confederate Armies, ser. 1, vol. 19, pt. 1, transcription. ↩
  2. Letterman, Medical Recollections, 19–24; Mary C. Gillett, The Army Medical Department, 1818–1865 (Washington, DC: Center of Military History, U.S. Army, 1987), 186–91, digitized chapter. ↩
  3. Letterman, Medical Recollections, 23–24; Glenna R. Schroeder-Lein, The Encyclopedia of Civil War Medicine (Armonk, NY: M. E. Sharpe, 2008), 11–17. ↩
  4. Gillett, Army Medical Department, 192–93. For the military circumstances of the withdrawal, see Perry D. Jamieson and Bradford A. Wineman, The Maryland and Fredericksburg Campaigns, 1862–1863 (Washington, DC: Center of Military History, U.S. Army, 2015), 11–13, open-access PDF. ↩
  5. Letterman, Medical Recollections, 24–30; Gillett, Army Medical Department, 191–92. ↩
  6. Letterman, Medical Recollections, 24–30. ↩
  7. Letterman, Medical Recollections, 30–31; Gillett, Army Medical Department, 191–93. ↩
  8. Letterman, Medical Recollections, 32–36, 42–43; Gillett, Army Medical Department, 192–93. ↩
  9. Letterman, Medical Recollections, 39–43; National Park Service, “Medicine and Medical Practices,” Antietam National Battlefield, accessed August 21, 2026. ↩
  10. Letterman, Medical Recollections, 39–42; Jamieson and Wineman, Maryland and Fredericksburg Campaigns, 22–34. ↩
  11. Letterman, Medical Recollections, 39–45; Jamieson and Wineman, Maryland and Fredericksburg Campaigns, 22–34. ↩
  12. Letterman, Medical Recollections, 42–44; Letterman, report dated March 1, 1863. ↩
  13. Letterman, Medical Recollections, 42–46; Letterman, report dated March 1, 1863. ↩
  14. Letterman, Medical Recollections, 45–46; Jamieson and Wineman, Maryland and Fredericksburg Campaigns, 34. For the limits of medical care available after evacuation, see John Tooker, “Antietam: Aspects of Medicine, Nursing and the Civil War,” Transactions of the American Clinical and Climatological Association 118 (2007): 215–23, open-access article. ↩
  15. Gillett, Army Medical Department, 193; Letterman, Medical Recollections, 44–46. ↩
  16. Letterman, Medical Recollections, 51–58; Gillett, Army Medical Department, 193–94. ↩
  17. Letterman, Medical Recollections, 59–64; Gillett, Army Medical Department, 194. ↩
  18. Letterman, Medical Recollections, 30–31, 66–70; Gillett, Army Medical Department, 194–96; Schroeder-Lein, Encyclopedia of Civil War Medicine, 14–17. ↩

Bibliography

Primary and Official Sources

  • Letterman, Jonathan. Medical Recollections of the Army of the Potomac. New York: D. Appleton, 1866. Digitized edition.
  • Letterman, Jonathan. Report dated March 1, 1863. In The War of the Rebellion: A Compilation of the Official Records of the Union and Confederate Armies. Series 1, vol. 19, pt. 1. Transcription.
  • National Park Service. “Medicine and Medical Practices.” Antietam National Battlefield. Accessed August 21, 2026. Site article.

Secondary Sources

  • Gillett, Mary C. The Army Medical Department, 1818–1865. Washington, DC: Center of Military History, U.S. Army, 1987. Digitized edition.
  • Jamieson, Perry D., and Bradford A. Wineman. The Maryland and Fredericksburg Campaigns, 1862–1863. Washington, DC: Center of Military History, U.S. Army, 2015. Open-access PDF.
  • Schroeder-Lein, Glenna R. The Encyclopedia of Civil War Medicine. Armonk, NY: M. E. Sharpe, 2008. Book record.
  • Tooker, John. “Antietam: Aspects of Medicine, Nursing and the Civil War.” Transactions of the American Clinical and Climatological Association 118 (2007): 215–23. Open-access article.