flagship vs spearhead

flagship

verb
  • To act as a flagship for. 

noun
  • The most important one out of a related group. 

  • The ship occupied by the fleet's commander (usually an admiral); it denotes this by flying his flag. 

  • The ship regarded as most important out of a group, e.g. a nation's navy or company's fleet. 

spearhead

verb
  • To drive or campaign ardently for, as an effort, project, etc. 

noun
  • The leading military unit in an attack. 

  • One who leads or initiates an activity (such as an attack or a campaign). 

  • The pointed head, or end, of a spear. 

  • A player who initiates attacking moves. 

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