During World War II, the condition we now call PTSD was most commonly labeled “combat exhaustion” or “battle fatigue.” In April 1943, the U.S. Army officially adopted “exhaustion” as the standard term for all psychiatric casualties near the front lines. But these were just the most widely used names in a long list of terms that shifted depending on whether symptoms appeared immediately or lingered for months after combat ended.
The Official Terms and Why They Changed
In World War I, the dominant term was “shell shock,” rooted in the belief that explosive blasts physically damaged the brain. By the time the Second World War began, military psychiatrists had moved away from that idea. They understood the condition was psychological, not caused by concussive force alone, and they wanted language that reflected temporary strain rather than permanent damage. The result was a deliberate shift toward words like “exhaustion” and “fatigue,” terms that implied a soldier could recover and return to duty.
Short-term battlefield reactions were called “exhaustion,” “battle exhaustion,” “combat fatigue,” or, among aircrews specifically, “flying stress.” These labels were applied to soldiers still near the front who showed acute psychological breakdown. For longer-lasting or more complex conditions, military doctors used terms like “psychoneurosis,” “war neurosis,” “cardiac neurosis,” and “effort syndrome.” The language was deliberately vague and optimistic, designed as much for morale as for medicine.
Old Sergeant Syndrome
One of the more specific WWII-era diagnoses was “Old Sergeant Syndrome,” describing experienced, previously effective soldiers who slowly deteriorated under sustained combat. These weren’t men who broke down after a single horrific event. They were seasoned fighters, often noncommissioned officers, who had endured months of combat and gradually lost their ability to function.
Army psychiatrists described these soldiers developing uncontrollable trembling, heavy sweating, and a growing reluctance to expose themselves to danger. They were described as “burnt out,” “worn out,” and “beat up.” Their ability to make quick decisions involving other soldiers’ lives eroded, and with it their self-confidence. In clinical interviews, they often spoke about devastating combat experiences in a flat, emotionless voice, only to break down weeping when recalling specific losses. That emotional numbness punctuated by sudden grief is strikingly similar to what clinicians now recognize as core features of PTSD.
The Scale of Psychiatric Casualties
The numbers from WWII reveal just how widespread combat-related psychological trauma was. Of the roughly 18 million men screened for military service, nearly 2 million were rejected at induction because of emotional or mental conditions. Another 750,000 who made it into the military were discharged early for the same reasons. Combined, about one in every seven men called for service was removed before or during their time in uniform due to psychiatric problems.
The Army had tried to prevent this. Induction screening during WWII was far more aggressive than it had been in the First World War, rejecting 10 to 15 percent of recruits for neuropsychiatric reasons compared to just 2 percent in WWI. But the strategy backfired. Despite the stricter screening, the psychiatric breakdown rate actually climbed to 12 percent of all troops, up from roughly 2 percent in WWI. At the worst point, in September 1943, more soldiers were being separated from the Army than were entering it, and the leading cause was psychoneurosis. The screening criteria simply could not predict who would break down under the specific horrors of sustained combat.
How the Military Treated It
The standard treatment approach during WWII followed a framework originally developed in World War I, built around three principles: proximity, immediacy, and expectancy (often abbreviated PIE). Soldiers showing psychiatric symptoms were treated as close to the front lines as possible, as quickly as possible, with the clear expectation that they would recover and return to their units. The logic was straightforward: evacuating a soldier far from the battlefield reinforced the idea that something was deeply wrong with him, making recovery less likely.
In practice, this meant rest, food, and brief supportive conversations at aid stations near the combat zone rather than long-term hospitalization in rear areas. The approach did get many soldiers back into action quickly, but it also meant that deeper, longer-lasting psychological wounds were often unaddressed. Soldiers who couldn’t recover within a few days were eventually evacuated and diagnosed with more chronic conditions like war neurosis or psychoneurosis.
From “Gross Stress Reaction” to PTSD
After the war ended, the psychiatric profession needed a formal diagnosis for what millions of veterans were experiencing. In 1952, the American Psychiatric Association published its first Diagnostic and Statistical Manual (DSM-I), which included a condition called “gross stress reaction.” It was designed for otherwise mentally healthy people who developed symptoms after extreme events like combat or disasters. This was the first official psychiatric diagnosis that directly connected traumatic experience to psychological illness.
But the diagnosis had a critical flaw: it assumed symptoms were temporary. If a veteran was still struggling years later, clinicians often attributed the problem to a pre-existing personality weakness rather than the trauma itself. Gross stress reaction was actually removed from the DSM’s second edition in 1968, leaving returning Vietnam veterans without a recognized diagnosis for their combat-related suffering. It wasn’t until 1980, with the publication of the DSM-III, that “post-traumatic stress disorder” finally entered the clinical vocabulary, giving a lasting name to what soldiers in every modern war had experienced under a rotating set of labels.
The progression from “shell shock” to “exhaustion” to “gross stress reaction” to “PTSD” reflects a slow, uneven recognition that combat trauma is neither a physical brain injury from explosions, nor simple fatigue, nor a character flaw. Each war forced the medical establishment to revisit what it thought it understood, and each time, the old terminology proved inadequate.