It's often discipline that takes over when courage fades. It's why training is so ingrained into soldiers. An amazing example would be the napoleonic era. If you weren't trained rigorously to, how would you stand in nice little lines while people shot you with cannon and musket?
Courage can happen on a small scale, and I suppose something like a soldier doing something that is extra surprising, almost like a 'critical' hit or something might be a way to implement it.
ie. Soldiers surprising an enemy by some unexpected means." but that's only if you needed to put it in.
