inroad vs onrush

inroad

noun
  • An advance into enemy territory, an attempted invasion; an encroachment, an incursion. 

  • Often followed by in, into, or on: initial progress made toward accomplishing a goal or solving a problem. 

onrush

noun
  • A forceful rush or flow forward. 

  • An aggressive assault. 

verb
  • To assault aggressively. 

  • To rush or flow forward forcefully. 

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