I could pay them double wages, throw them a party and generally make a big fuss about them. But. That might just upset the rest of the army, since the chaps who are feeling sorry for themselves did just get their backside's kicked by the enemy.
Best case of MORALE LOW I've experienced so far, is when I had a squadron of light cavalry work on their horsemanship at a stud farm. They developed a Sick List like it was going out of fashion and then their morale dropped. Sick List was accumulating at one point a month and it didn't look good for the squadron, so I cancelled the horse obedience training 2 months before completion and then the troops became Morale Low. Perhaps would have been interesting to have allowed the obedience training to complete and see how high a Sick List score was reached.