bulwark vs defend

bulwark

verb
  • To provide protection of defense for something. 

  • To fortify something with a wall or rampart. 

noun
  • A defensive wall or rampart. 

  • A defense or safeguard. 

  • 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. 

defend

verb
  • To ward off attacks against; to fight to protect; to guard. 

  • To focus one's energies and talents on preventing opponents from scoring, as opposed to focusing on scoring. 

  • To attempt to retain a title, or attempt to reach the same stage in a competition as one did in the previous edition of that competition. 

  • To call a raise from the big blind. 

  • To support by words or writing; to vindicate, talk in favour of. 

  • To make legal defence of; to represent (the accused). 

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