Originally Posted by Strongbow

A book called “h**l in the Pacific” by Jonathon Lewis and Ben Steele published in 2001 has the following about battle fatigue cases. I will directly quote from the chapter “h**l’s Teeth” on page 151.

Those in the front line faced the most severe stress. Men soiled their pants from fear; trapped by artillery fire with nowhere to dig in, they trembled so badly they could not stop shaking; they were so on edge at night that it was advisable to whisper to a buddy to wake him up when it was his turn to keep watch: if he was touched he might come up fighting with his K-bar knife. They collapsed from heat exhaustion having fought for days, in searing heat, without receiving any fresh water supplies; and through it all they endured the stench of putrefying flesh and the sight of maggots devouring the dead.

The numbers of men who cracked under such intense pressure grew as the war rolled towards Tokyo and encountered even more fanatical resistance. The battle for the tiny volcanic island of Iwo Jima, in which close to 6000 US Marines died, had approximately 4000 evacuations for battle fatigue (out of a total of 18,000 evacuations). Later that year on Okinawa, the most bloody island invasion of the war, some 26,000 men were evacuated as neuro-psychological cases.

Other sources have documented US Marine deaths on Iwo Jima to be higher.