death march vs requiem

death march

noun
  • Synonym of dead march (“mournful music for a funeral etc.”) 

  • A forced movement of people, on foot, in such circumstances that many die during the journey. 

  • A project that requires a stretch of unsustainable overwork, or whose participants feel it is destined to fail. 

requiem

noun
  • A piece of music composed to honor a dead person. 

  • A large or dangerous shark, specifically, (zoology) a member of the family Carcharhinidae. 

  • A mass (especially Catholic) to honor and remember a dead person. 

  • A musical composition for such a mass. 

How often have the words death march and requiem occurred in a corpus of books? (source: Google Ngram Viewer )