Portrait of Jonathan Letterman
Father of Battlefield Medicine
Medical Director – Army of the Potomac 1862-1864


Dr. Jonathan Letterman:

Father of Modern Emergency Medicine


Dr. Jonathan Letterman is considered the father of modern military and emergency medicine. As Medical Director of the Federal Army of the Potomac, Letterman transformed the Medical Corps from an uncoordinated and poorly-supplied operation into one of the most finely-tuned and efficient organizations in the Federal Army.

A native of Pennsylvania, Letterman graduated in 1849 from the Jefferson Medical College of Philadelphia. Soon after, Letterman accepted a commission as Assistant Surgeon in the U. S. Army, serving in posts across the country, and in several campaigns against Native Americans in the Southwest and Florida.

Letterman assumed command as Surgeon and Medical Director of the Army of the Potomac in July 1862. His first major contribution was the creation of a robust and independent Ambulance Corps. Ambulances were used prior to Letterman’s order, but were too few, poorly staffed and organized, and frequently detained for unrelated purposes by non-medical officers. Under Letterman’s orders, each regiment or battery was assigned its own ambulances, staffed by well-trained and specifically designated stretcher-bearers and drivers. Officers were placed in charge of ambulances at each level of command, and operated independently from the authority of non-medical officers. Ambulances were forbidden to any use but the transportation of wounded and medical supply, freeing them from abuse and promoting greater efficiency in removing wounded from the field.

Letterman’s greatest trial as Medical Director came in the Antietam Campaign of September 1862. This campaign was Letterman’s first real opportunity to implement plan. This included the establishment of medical operations before a battle to treat wounded more quickly. As the Army of the Potomac moved through Frederick, Maryland, Letterman selected the city as a hospital center and medical supply depot because of its extensive road network and direct access by rail to Washington and Baltimore. Letterman designated public and private buildings in the Middletown area to serve as hospitals for the Battle of South Mountain. At Antietam, Letterman and his staff again prepared the medical response in anticipation of casualties, this time on a much larger scale. This preparation seems like common sense today, but at the time, it was quite innovative.

Beginning at Antietam, Letterman also developed an orderly and efficient system for the treatment of wounded soldiers. This began right on the firing lines, where regimental surgeons were the first responders. From the front, the wounded were moved by ambulance along pre-determined evacuation routes to division field hospitals, most of which had been set prior to the battle. At each field hospital, “dressers” performed basic triage, sorting patients for treatment by priority rather than order of arrival. After being stabilized, most patients were transported to long-term recovery hospitals in Frederick or sometimes to Baltimore, Washington, and Philadelphia. Letterman also created two long-term hospitals on the battlefield – the first of their kind – at Smoketown and Keedysville. This kind of evacuation and treatment in stages remains fundamental in handling battlefield casualties today.

Antietam was a success for Letterman and the Medical Corps. September 17, 1862 was the bloodiest day in American history and the largest battle of the war to that date. It left over ten thousand Federal soldiers wounded, and thousands more Confederates, left by their retreating army. Within twenty-four hours of the battle, all Federal wounded had been secured in hospitals, and within forty-eight hours the abandoned Confederate wounded were also secured. This contrasted starkly to aftermath of previous battles, like First Bull Run, where wounded had languished on the field for over a week, often dying from exposure.

Of the problems at Antietam, lack of supplies was the greatest. The Army of the Potomac’s supply system became jammed at Frederick and desperately needed medical supplies failed to reach the battlefield until days after the fighting. Additionally, some hospitals had been erected on the field unbeknownst to Letterman or his staff and went unattended for lengthy periods of time. Letterman also faced a lack of record-keeping in most field hospitals, making it difficult to account for personnel and supplies.

Inspired by the lessons of Antietam, Letterman issued orders in October of 1862 to reorganize the Army of the Potomac’s Medical Corps. His orders called for the establishment of division hospitals at the outset of each engagement. All hospitals would have one surgeon in charge, an assistant surgeon to provide supplies, and another to keep records. Each hospital would also select three surgeons, based on skill rather than rank, to perform operations while others assisted or performed other duties. Practices which had been successful at Antietam remained part of the Letterman plan, including the staged evacuation system and basic triage at field hospitals. Letterman also addressed the problem of supply by separating medical supplies from the regular army quartermaster and reduced waste by changing the distribution of medical supplies at the regimental level. Though he continued to tweak and improve it, Letterman’s system remained essentially unchanged after the fall of 1862.

Letterman considered the first true test of his new system to be the Battle of Fredericksburg in December 1862, where the Medical Corps performed with great satisfaction. Perhaps Letterman’s greatest test came at Gettysburg in July 1863, where the Federal Army alone suffered over 14,000 causalities. To care for nearly 4,000 Federal and Confederate troops too severely wounded to be moved, a large general tent hospital, dubbed “Camp Letterman,” was established just north of town.

In January 1864, Letterman left the Army of the Potomac, eventually resigning his commission and moving to California. He published his memoirs, Medical Recollections of the Army of the Potomac in 1866, and served as coroner of San Francisco from 1867 until his death in 1872 at the age of 47.

Letterman is among the most important figures in American medical history. His work during the Civil War has remained fundamental to the modern Army Medical Corps and the handling of casualties on and off the battlefield. Letterman’s ideas have also been central to civilian emergency medicine, disaster relief, and emergency management around the world. The Letterman Army Hospital, which operated in San Francisco for nearly a century, was named in his honor. Major General Paul Hawley, Chief Surgeon of the European Theater in the Second World War, said of Letterman, “I often wondered whether, had I been confronted with the primitive system which Letterman fell heir to at the beginning of the Civil War, I could have developed as good an organization as he did. I doubt it. There was not a day during World War II that I did not thank God for Jonathan Letterman.”

The Barton Patient Rolls

Search through the patient list from Clara Barton’s records.

The Barton Rolls

Frederick Patients after the Battle of Antietam

Search through our list below of patients that were treated in Frederick after the Battle of Antietam.