(...) two groups of people who said they were very afraid of snakes were shown slides of snakes while listening to what they believed was their heart rate. Occasionally one group would see a slide with the word “shock” printed on it. They were given a jolt of electricity when they saw this slide, and the researchers falsely increased the sound of the beating of their hearts in the monitor. When they later were asked to hold a snake, they were far more likely to give it a shot than the group who didn’t see the shock slide and hear a fake increase in heart rate. They had convinced themselves they were more afraid of being shocked than of snakes and then used this introspection to truly be less afraid.
"You are not so smart", David McRaney
This made me think of how greatly the fear of becoming a prisoner of war in Siberia reportedly motivated German troops in 1943-1944 (the more common explanation of stubborn defences in 1945 was concern about the safety of German civilians).
I suppose there are many ways how creating an artificially elevated fear of something else can be used to provoke greater courage on a mission. "Honour codes" created the fear of losing one's (or one's family's) honour, for example.
And obviously it's no good idea to help the opposing forces' leaders doing their job; good treatment of prisoners (and reports to home through the international red cross) is a very prudent strategy.