n.
  - a sustained fight between organized armed forces.
 - a lengthy and difficult conflict or struggle.
 
v.
 fight or struggle tenaciously with an opponent or to achieve something.
 
  Phrase
  
    - battle royal
 (pl. battles royal)
 a fiercely contested fight or dispute.  - battle stations
 chiefly US the positions taken by military personnel in preparation for battle. 
   
  Derivative
  
  Etymology
  ME: from OFr. bataille (n.), bataillier (v.), based on late L. battualia ‘military or gladiatorial exercises’, from L. battuere ‘to beat’.