How many soldiers were shell shocked in World War 1?

During World War I, it is estimated that around 500,000 soldiers were affected by what was then termed "shell shock," a condition now recognized as a form of post-traumatic stress disorder (PTSD). The psychological impact of the war, coupled with the intense bombardments and trench warfare, contributed to this high number. Many soldiers experienced severe anxiety, depression, and other debilitating symptoms, highlighting the war's profound impact on mental health. The understanding of such conditions has evolved significantly since then, leading to better recognition and treatment in modern contexts.