The compassion we feel normally is biased and mixed with attachment. Genuine compassion flows towards all living beings, particularly your enemies. If I try to develop compassion towards my enemy, it may not benefit him directly, he may not even be aware of it. But it will immediately benefit me by calming my mind. On the other hand, if I dwell on how awful everything is, I immediately lose my peace of mind.
Nothing shocks our moral feelings so deeply as cruelty does. We can forgive every other crime, but not cruelty. The reason for this is that it is the very opposite of compassion.
Those who have compassion when they do battle will be victorious. Those who likewise defend themselves will be safe. Heaven will rescue and protect them with compassion.
When we speak of a calm state of mind or peace of mind, we shouldn't confuse that with an insensitive state of apathy. Having a calm or peaceful state of mind doesn't mean being spaced out or completely empty. Peace of mind or a calm state of mind is rooted in affection and compassion and is sensitive and responsive to others.