at war vs belligerent

at war

prep
  • (typically with with or against) Vigorously opposed (to); in strong conflict (with). 

  • Fighting in a war. 

belligerent

noun
  • A state or other armed participant in warfare 

adj
  • Eager to go to war, warlike. 

  • Engaged in warfare, warring. 

  • Of or pertaining to war. 

  • Uncooperative. 

  • Aggressively hostile, eager to fight. 

  • Acting violently towards others. 

How often have the words at war and belligerent occurred in a corpus of books? (source: Google Ngram Viewer )