What does the word redoubt mean?

Usage examples for redoubt

  1. " You see what's happened," explained the O. C. " The place would be so obviously dominated by the capture of this ridge that the beggars haven't thought it worth while turning it into a redoubt. – With Haig on the Somme by D. H. Parry
  2. Hidden away there in a wrinkle of the hill they are waiting for some unknown reason, and the conquerors of the great Redoubt seem doomed. – VC -- A Chronicle of Castle Barfield and of the Crimea by David Christie Murray