bulwark vs protector

bulwark

noun
  • A defense or safeguard. 

  • A defensive wall or rampart. 

  • A breakwater. 

  • Any means of defence or security. 

  • The planking or plating along the sides of a nautical vessel above her gunwale that reduces the likelihood of seas washing over the gunwales and people being washed overboard. 

verb
  • To fortify something with a wall or rampart. 

  • To provide protection of defense for something. 

protector

noun
  • Someone who protects or guards, by assignment or on their own initiative. 

  • A state or other subject under international law, exercising a protectorate over another subject in international law. 

  • One having the care of the kingdom during the king's minority; a regent. 

  • A device or mechanism which is designed to protect. 

  • One who prevents interference. 

  • A cardinal, from one of the more considerable Roman Catholic nations, who looks after the interests of his people at Rome; also, a cardinal who has the same relation to a college, religious order, etc. 

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