July 1 marked 150 years since the beginning of the Battle of Gettysburg, a crucial victory for the Union and a turning point in the Civil War. But it came at an enormous cost to both sides — thousands of soldiers were killed and tens of thousands more were wounded.

However, it might have been even worse had it not been for a surgeon named Jonathan Letterman, who served as the chief medical officer of the Union's Army of the Potomac. He presided over some of the bloodiest battles in U.S. history and, over the course of a single year, revolutionized military medicine.

Scott McGaugh has just released his biography of Letterman, called Surgeon in Blue. He joins NPR's Rachel Martin to discuss the father of battlefield medicine, what conditions were like before he came along and the legacy he left behind.

Interview Highlights

On the state of medicine in the United States at the start of the Civil War

"In a word, horrific. Military doctors were poorly qualified from a medical standpoint. They didn't know what caused infections, bacteria, anything of that sort. There was no ambulance system, so the early battles, such as Bull Run, left thousands of men wounded on the battlefield for days, some of them dying of dehydration and thirst. They were weakened to begin the battle because [the] Army diet was horrible, in the sense of salt pork, weevil-filled biscuits and alcohol as the daily ration. And their odds of survival, if they were wounded, were not very good in the early battles."

On what happened to wounded soldiers at the battle of Bull Run

"They had very little place to go. They were dependent upon a few slackers, derelicts and Army band members who were typically assigned as ambulance crews. The ambulances were not nearly enough in number. No one expected to see the kinds of casualty numbers of Bull Run, which obviously became a harbinger of battles to come. If you were lucky enough to be ambulatory, you might have walked or hitched a ride back to Washington, and then walked the streets for several days looking for a hospital bed because there weren't nearly enough hospitals or hospital capacity in the early days of the Civil War."

On how Letterman improved Civil War medicine

"He stood in a remarkably fortuitous position in time. The commanding general, George McClellan, was something of a reformer; the surgeon general was a very deep-thinking reformer by the name of William Hammond, a young man. And that gave Letterman the opportunity to apply a very keen, analytical, holistic mind to health care, not just on the battlefield but before ever reaching the battlefield. And he was able to very quickly issue new regulations, make them mandatory with real authority, that defined and codified new standards in nutrition, camp hygiene, how and when latrines were dug and when they were covered, the disposal of lice-ridden uniforms. Because at the time when he took over, he was faced with a disease rate of nearly 40 percent."

On what it was like before Letterman developed the modern ambulance corps

"Prior to that, military officers routinely commandeered wagons intended as ambulances for their personal use and for their baggage with no repercussions. ... Luggage, personal belongings, even their servants in some cases. So one of the very first things Letterman did was acquire the authority from Gen. McClellan to hold military officers and medical officers accountable. [He] developed a corps of trained ambulance drivers and stretcher bearers, so he added a level, or created a level, of professionalism that had not been in existence."

On how keeping soldiers healthy wasn't just about compassion

"He believed that a healthier Army — wounded men who were kept with their units and treated in hospitals near the Army — were much more likely to return to battle [and] gave Gen. McClellan a stronger, more viable fighting force. And if that made him more effective, that might lead to a faster end to the war and the ability for everyone to go home."

On Letterman's legacy

"Letterman clearly demonstrated that speed to care, what was once called 'the golden hour,' was absolutely crucial to a soldier's chances of survival.

"A refined triage concept, beginning with those paramedics ... alongside the stretcher, to the aid station, to the field hospital, all the way to a specialized hospital in the United States today. All those concepts, those principles, that all began with Jonathan Letterman. And today it's a hallmark of battlefield medicine, to a point where in World War II, 30 percent of soldiers succumbed to their wounds. Today, it's less than 10 percent."

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