I'm going to take a guess and say, "honor." Which is definitely not a good enough reason to just die.
That.
Also, if I was given the choice of
a) a comfortable death at home, by binging on sleeping pills or whatever;
or
b) an uncomfortable death in dirt, suffering, fear, routine abuse, stress, sleep deprivation, pain, ... on the battlefield;
I know which one I'd pick! Sure as fuck not b)!