Wiktionary
n. Dying (especially in battle) for one's country or other cause.
Usage examples of "supreme sacrifice".
So when the priests left, I told her that I was willing to make the supreme sacrifice.
The colonel seemed caught in the same heroic ecstasy that had impelled his Obersturmunddrang, or whatever the hell that German was, to the supreme sacrifice.
Or if they shrank from the supreme sacrifice, it never occurred to them that they acted otherwise than basely in preferring their personal existence to the interests of their country.
His belief notwithstanding, he could not have helped doubting or being gripped by the fear of death at the moment of his supreme sacrifice.
For this she had dared everything, had made the supreme sacrifice.
What a thing this holy war is, in which with one supreme sacrifice men may atone for all their evils!