In the summer of 1862, John Hildt lost a limb. Then he lost his mind.

The 25-year-old corporal from Michigan saw combat for the first time at the Seven Days Battle in Virginia, where he was shot in the right arm. Doctors amputated his shattered limb close to the shoulder, causing a severe hemorrhage. Hildt survived his physical wound but was transferred to the Government Hospital for the Insane in Washington D.C., suffering from “acute mania.”

Hildt, a laborer who’d risen quickly in the ranks, had no prior history of mental illness, and his siblings wrote to the asylum expressing surprise that “his mind could not be restored to its original state.” But months and then years passed, without improvement. Hildt remained withdrawn, apathetic, and at times so “excited and disturbed” that he hit other patients at the asylum. He finally died there in 1911—casualty of a war he’d volunteered to fight a half-century before.

The Civil War killed and injured over a million Americans, roughly a third of all those who served. This grim tally, however, doesn’t include the conflict’s psychic wounds. Military and medical officials in the 1860s had little grasp of how war can scar minds as well as bodies. Mental ills were also a source of shame, especially for soldiers bred on Victorian notions of manliness and courage. For the most part, the stories of veterans like Hildt have languished in archives and asylum files for over a century, neglected by both historians and descendants.

This veil is now lifting, in dramatic fashion, amid growing awareness of conditions like post-traumatic stress disorder. A year ago, the National Museum of Civil War Medicine mounted its first exhibit on mental health, including displays on PTSD and suicide in the 1860s. Historians and clinicians are sifting through diaries, letters, hospital and pension files and putting Billy Yank and Johnny Reb on the couch as never before. Genealogists have joined in, rediscovering forgotten ancestors and visiting their graves in asylum cemeteries.

“We’ve tended to see soldiers in the 1860s as stoic and heroic—monuments to duty, honor and sacrifice,” says Lesley Gordon, editor of Civil War History, a leading academic journal that recently devoted a special issue to wartime trauma. “It’s taken a long time to recognize all the soldiers who came home broken by war, just as men and women do today.”

Counting these casualties and diagnosing their afflictions, however, present considerable challenges. The Civil War occurred in an era when modern psychiatric terms and understanding didn’t yet exist. Men who exhibited what today would be termed war-related anxieties were thought to have character flaws or underlying physical problems. For instance, constricted breath and palpitations—a condition called “soldier’s heart” or “irritable heart”—was blamed on exertion or knapsack straps drawn too tightly across soldiers’ chests. In asylum records, one frequently listed “cause” of mental breakdown is “masturbation.”

Also, while all wars are scarring, the circumstances of each can wound psyches in different ways. The relentless trench warfare and artillery bombardments of World War I gave rise to “shell shock” as well as “gas hysteria,” a panic prompted by fear of poison gas attacks. Long campaigns in later conflicts brought recognition that all soldiers have a breaking point, causing “combat fatigue” and “old sergeant’s syndrome.” In Vietnam, the line between civilians and combatants blurred, drug abuse was rampant and veterans returned home to an often-hostile public. In Iraq and Afghanistan, improvised explosive devices put soldiers and support personnel at constant risk of death, dismemberment and traumatic brain injury away from the front.

Civil War combat, by comparison, was concentrated and personal, featuring large-scale battles in which bullets rather than bombs or missiles caused over 90 percent of the carnage. Most troops fought on foot, marching in tight formation and firing at relatively close range, as they had in Napoleonic times. But by the 1860s, they wielded newly accurate and deadly rifles, as well as improved cannons. As a result, units were often cut down en masse, showering survivors with the blood, brains and body parts of their comrades.

Many soldiers regarded the aftermath of battle as even more horrific, describing landscapes so body-strewn that one could cross them without touching the ground. When over 5,000 Confederates fell in a failed assault at Malvern Hill in Virginia, a Union colonel wrote: “A third of them were dead or dying, but enough were alive to give the field a singularly crawling effect.”

Wounded men who survived combat were subject to pre-modern medicine, including tens of thousands of amputations with unsterilized instruments. Contrary to stereotype, soldiers didn’t often bite on bullets as doctors sawed off arms and legs. Opiates were widely available and generously dispensed for pain and other ills, causing another problem: drug addiction.

Nor were bullets and shells the only or greatest threat to Civil War soldiers. Disease killed twice as many men as combat. During long stretches in crowded and unsanitary camps, men were haunted by the prospect of agonizing and inglorious death away from the battlefield; diarrhea was among the most common killers.

Though geographically less distant from home than soldiers in foreign wars, most Civil War servicemen were farm boys, in their teens or early 20s, who had rarely if ever traveled far from family and familiar surrounds. Enlistments typically lasted three years and in contrast to today, soldiers couldn’t phone or Skype with loved ones.

These conditions contributed to what Civil War doctors called “nostalgia,” a centuries-old term for despair and homesickness so severe that soldiers became listless and emaciated and sometimes died. Military and medical officials recognized nostalgia as a serious “camp disease,” but generally blamed it on “feeble will,” “moral turpitude” and inactivity in camp. Few sufferers were discharged or granted furloughs, and the recommended treatment was drilling and shaming of “nostalgic” soldiers—or, better yet, “the excitement of an active campaign,” meaning combat.

At war’s end, the emotional toll on returning soldiers was often compounded by physical wounds and lingering ailments such as rheumatism, malaria and chronic diarrhea. While it’s impossible to put a number on this suffering, historian Lesley Gordon followed the men of a single unit, the 16th Connecticut regiment, from home to war and back again and found “the war had a very long and devastating reach.”

The men of the 16th had only just been mustered in 1862, and barely trained, when they were ordered into battle at Antietam, the bloodiest day of combat in U.S. history. The raw recruits rushed straight into a Confederate crossfire and then broke and ran, suffering 25 percent casualties within minutes. “We were murdered,” one soldier wrote.

In a later battle, almost all the men of the 16th were captured and sent to the notorious Confederate prison at Andersonville, where a third of them died from disease, exposure and starvation. Upon returning home, many of the survivors became invalids, emotionally numb, or abusive of family. Alfred Avery, traumatized at Antietam, was described as “more or less irrational as long as he lived.” William Hancock, who had gone off to war “a strong young man,” his sister wrote, returned so “broken in body and mind” that he didn’t know his own name. Wallace Woodford flailed in his sleep, dreaming that he was still searching for food at Andersonville. He perished at age 22, and was buried beneath a headstone that reads: “8 months a sufferer in Rebel prison; He came home to die.”

Others carried on for years before killing themselves or being committed to insane asylums. Gordon was also struck by how often the veterans of the 16th returned in their diaries and letters to the twin horrors of Antietam and Andersonville. “They’re haunted by what happened until the end of their lives,” she says.

Gordon’s new book on the 16th, A Broken Regiment, is but one of many recent studies that underscore the war’s toll on soldiers. In another, Living Hell: The Dark Side of the Civil War, historian Michael Adams states on the first page that his book describes “the vicious nature of combat, the terrible infliction of physical and mental wounds, the misery of soldiers living amid corpses, filth, and flies.”

Not all scholars applaud this trend, which includes new scholarship on subjects such as rape, torture and guerrilla atrocities. “All these dark elements describe the margins not the mainstream of Civil War experience,” says Gary Gallagher, a historian at the University of Virginia who has authored and edited over 30 books on the war. While he welcomes the fresh research, he worries that readers may come away with a distorted perception of the overall conflict. The vast majority of soldiers, he adds, weren’t traumatized and went on to have productive postwar lives.