Post-Traumatic Stress Disorder (PTSD) is a mental health condition that affects many veterans—and civilians as well. PTSD can develop after someone experiences or witnesses a traumatic event, such as combat, training accidents, or military sexual trauma. Although the condition is now widely recognized, it was not always well understood by the medical or military communities.

In the aftermath of World War II, the Vietnam War, and other major conflicts, veterans often exhibited symptoms we now associate with PTSD, but at the time, these were referred to as "shell shock" or "combat fatigue." Department of Defense press releases and historical reviews have acknowledged these early cases as important steps in recognizing and understanding PTSD. Ongoing research continues to improve the diagnosis, treatment, and support for those suffering from the psychological wounds of war.