I always regard life as precious

If only life was black and white. I am opposed to the death penalty but I have to ask myself:

How to deal with an invading army? ;
Should troops be sent in to defend the country when, inevitably, not all will come back? ;
Is aerial bombardment of an aggressor's war machine acceptable, knowing there will be "collateral damage"? ;
Is military action in another country, to remove a despot who is threatening the lives of his own people, acceptable?

If sacrificing life for the common good is acceptable in theses circumstances, what is the argument against capital punishment?

My own feeling is that capital punishment wouldn't have the desired effect, or be of limited value, as murders are often crimes of passion with no thought of the consequences. Mass shooters often turn their guns on themselves. My biggest objection is that miscarriages of justice can't be corrected.

DC