last full measure

Noun

 * 1)  A person's life, when lost through death in service to a nation or cause, particularly as a member of a military force in war or a semi-militarized organization such as a police force or civil defense corps, e.g. fire departments.

Usage notes
Not normally applied to death in service to a nation or cause outside of a military or semi-military context; for example the deaths by starvation of scientists defending the Pavlovsk Experimental Station gene bank in Leningrad during World War II, refusing to consume irreplaceable scientific samples even to save themselves, are not usually characterized this way, despite those deaths being regarded sentimentally and as noble acts.