Dying (being killed) is the essence of warfare. To die for one’s country (or any sacred entity) constitutes a demonstration of commitment or devotion or sincerity.

That for which we die becomes real or true.

The nature of the entity or idea for which human beings die and kill is fungible, the mechanism the same regardless of the nature of the idea: death--and memorials erected in the name of those who have died—testify to the reality of the sacred ideal.

Death and memorialization perform a validation function.

Death as the Principle of Verification (click link please).