back down vs withstand

back down

verb
  • To withdraw from a commitment or position. 

  • To take a less aggressive position in a conflict than one previously has or has planned to. 

withstand

verb
  • To resist or endure (something) successfully. 

  • To oppose (something) forcefully. 

How often have the words back down and withstand occurred in a corpus of books? (source: Google Ngram Viewer )