Final answer:
PTSD was officially recognized as a disorder in the DSM-III in 1980, following observations of veterans, although earlier conflicts had similar symptoms described as shell shock or combat fatigue.
Step-by-step explanation:
Post-traumatic stress disorder (PTSD) formally came into being as a recognized disorder in 1980 with its inclusion in the third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III) by the American Psychiatric Association. The recognition of PTSD as a distinct condition followed extensive observation of returning military veterans, notably during and after the Vietnam War, where it became clear many servicemen suffered from severe psychological trauma. Historically, terms like "shell shock" and "combat fatigue" were used to describe similar symptoms in soldiers from previous conflicts such as World War I and World War II. While initially many considered the psychological impact of war as a normal reaction to trauma or a sign of personal weakness, gradual shifts in understanding acknowledged the complex nature of PTSD, leading to better identification of the disorder and efforts at providing appropriate treatments.