>>After discovering lots of their soldiers were reluctant to kill, the
>>armed forces decided that there needed to be a deliberate and
>>concerted attempt to instill killer instinct into people.
>
>... because that could never go horribly wrong later.

I recall reading a news report about this; on top of all the more obvious (but less demonstrable, at least from unclassified sources) ways it could go horribly wrong, it's thought to be at least partially responsible for the massive increase in PTSD in veterans of more recent wars.