I leave this as a declaration of intent, so no one will be confused.
One: "Si vis pacem, para bellum." Latin. Boot Camp Sergeant made us recite it like a prayer. "Si vis pacem, para bellum - If you want peace, prepare for war."
Two: Frank Castle is dead. He died with his family.
Three: in certain extreme situations, the law is inadequate. In order to shame its inadequacy, it is necessary to act outside the law. To pursue... natural justice. This is not vengeance. Revenge is not a valid motive, it's an emotional response.

No, not vengeance. Punishment.