dogface vs foot soldier

dogface

noun
  • A foot soldier, especially during World War II. 

  • Either of two pierid butterflies of the New World genus Zerene. 

  • An ugly person. 

foot soldier

noun
  • A soldier who fights on foot; an infantryman 

  • A rank and file member of an institution, or supporter of a cause. 

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