DOD changed the language of status of soldiers to "battle fatigue" when in fact they had suffered mental breakdowns in Vietnam. The "rationale" was that if the military of North Vietnam discovered how many US soldiers were having breakdowns in the field, NV would be emboldened towards victory. So the sham was maintained. And worse, as the US soldiers had become disabled and had to be removed back to US Mainland veterans' hospitals, they weren't treated for their mental breakdowns. The charade continued into the wards of Walter Reed, etc. and they were literally treated for battle fatigue, a syndrome that suggested with enough rest, these soldiers would be back on their feet and ready to return to the war theater in Vietnam.
My friend, Tony, went through this. He had PTSD for decades before the VA actually approved the correct treatment for him. Every night, nightmares. He figured out by reading medical articles that he had suffered a nervous breakdown during Operation Hastings. (He was only two survivors in a platoon of 24 where they were unknowingly sent out as "bait" for the NV with a larger ring of US military that would surround the NV. It didn't obviously didn't end well.