trials by fire

Noun

trial by fire (countable and uncountable, plural trials by fire)

1. A test in which a person is exposed to flames in order to assess their truthfulness, commitment, courage etc.
   • “[I]t seems to me Fra Francesco is the greater hero, for he offers to enter the fire for the truth, though he is sure the fire will burn him.” . . .
     “It is true, Messer Segretario,” said the shopkeeper, with subdued impatience. “But will you favour us by interpreting the Latin?”
     “Assuredly,” said...1863, George Eliot, chapter 63, in Romola
2. A situation in which a soldier or other combatant faces the discharge of opposing weapons, as a test of their fortitude.
   • French troops, submitting to a trial by fire, drew toward the German forts, capturing and holding some machine-gun nests.1939 September 8, “Swiss Hear Heavy Guns”, in Reading Eagle, USA, retrieved 15 Jul 2012, page 8
3. (broadly, idiomatic) Any ordeal which tests one's strength, endurance or resolve.
   • But take it all in all, the overland trail was a trial by fire. One gets a notion of its deadliness from the fact that over five thousand people died of cholera alone.1918, Stewart Edward White, chapter 5, in The Forty-Niners