In the early-to-mid-20th century, the prevailing view of trauma shifted toward seeing it as a response to discrete external events, particularly the horrors of war and other large-scale catastrophes. While psychoanalysts during the interwar period gave limited attention to real-life trauma, military psychiatrists observed acute psychological breakdowns among soldiers that could not be ignored. World War I (1914–1918), in particular, brought the phenomenon of “shell shock” into public awareness. Soldiers exposed to artillery bombardment and life-threatening conditions developed symptoms such as trembling, paralysis, nightmares, anxiety attacks, and dissociation. Initially, these symptoms were attributed to physical brain injuries from exploding shells—hence the term shell shock. However, clinicians soon noted that similar breakdowns occurred in soldiers who had not been near explosions, leading to the realization that psychological stress, not physical trauma, was the root cause (Jones & Wessely, 2005).
The term “war neurosis” gradually replaced shell shock, emphasizing the emotional and psychological impact of combat. During World War I, treatment for such conditions varied. Some soldiers received rest and rehabilitation, while others were rapidly returned to the front lines or subjected to punitive measures. Despite the inconsistency in care, the war exposed that “normal” individuals could suffer devastating psychological effects from traumatic experiences, challenging earlier assumptions that only those with weak character would break down under pressure (Shephard, 2001).
World War II (1939–1945) saw similar issues arise, with terms such as “combat fatigue” and “battle exhaustion” describing the psychological toll of prolonged deployment. Military psychiatrists during WWII developed the “PIE” principles—Proximity, Immediacy, and Expectancy—for managing acute stress reactions. These guidelines recommended treating soldiers near the front, as soon as symptoms emerged, and with the expectation of full recovery and return to duty (Trimble, 1981). While this method proved effective for short-term stabilization, many veterans returned from combat with enduring psychological wounds.
By the end of the war, it was clear that intense external stressors—especially those involving life-threatening violence—could produce a reliable cluster of mental health symptoms across different conflicts. Despite this, formal psychiatric nosology struggled to accommodate these findings. The first Diagnostic and Statistical Manual of Mental Disorders (DSM-I) published in 1952 included “Gross Stress Reaction” as a transient diagnosis for individuals experiencing an acute reaction to extreme stress (American Psychiatric Association [APA], 1952). However, the diagnosis assumed these symptoms would resolve within six months, after which a different condition would be assigned if symptoms persisted.
During the 1950s and 1960s, broader social events brought trauma back into focus. Holocaust survivors, for example, often exhibited enduring psychological distress, although this was frequently mischaracterized as survivor’s guilt or chronic grief rather than trauma. Similarly, survivors of natural disasters and severe accidents were observed to have long-lasting symptoms, but psychiatric classification systems remained inadequate. When the DSM-II was published in 1968, the category “Gross Stress Reaction” was removed entirely. The only relevant entry was “Adjustment Reaction to Adult Life,” a vague and non-specific diagnosis that failed to capture the chronic, intrusive symptoms now recognized as classic trauma responses (APA, 1968).
A significant shift came during and after the Vietnam War (1955–1975). A significant number of veterans returned to civilian life suffering from nightmares, flashbacks, emotional numbing, hypervigilance, and profound difficulties in relationships and daily functioning. This collection of symptoms, dubbed “post-Vietnam syndrome,” brought renewed attention to trauma in military populations (Lifton, 1973). Simultaneously, the women’s rights movement drew attention to the psychological harm caused by rape, domestic violence, and child abuse—forms of trauma that had historically been ignored or dismissed.
In 1974, psychiatrists Ann Burgess and Lynda Holmstrom introduced the concept of Rape Trauma Syndrome, identifying a predictable pattern of psychological symptoms following sexual assault that closely mirrored combat trauma (Burgess & Holmstrom, 1974). Clinicians also began describing Battered Women Syndrome and the long-term effects of childhood abuse. These contributions emphasized that trauma was not confined to the battlefield and that interpersonal trauma—especially when repeated—could have equally devastating consequences.
By the late 1970s, the accumulated evidence from war veterans, sexual assault survivors, and abused children led to the formal recognition of a trauma-based diagnosis. In 1980, DSM-III introduced Post-Traumatic Stress Disorder (PTSD) as a distinct diagnostic category. PTSD was defined as a psychological response to an event that was “outside the range of usual human experience,” with symptom clusters that included intrusive re-experiencing, avoidance/numbing, and heightened arousal (APA, 1980). This diagnostic milestone formally validated the experiences of trauma survivors and marked the beginning of modern psychotraumatology.