battle royal

battle royal /͵bætlʹrɔıəl/ (...a battle involving many combatants;||general mayhem; a free-for-all fight; a contest with fists or cudgels in which more than two are engaged; a mêlée =>a heated discussion) — 1) генеральное сражение; 2) шутл. баталия, побоище, общая свалка (о драке, споре и т. п.)

Example 1: We just had a battle royal with the locals. (Tweets)

Example 1: The ambition of every individual is quite the opposite, — to give least for most; and as a result, living in a tooth-and-nail society, battle royal is waged by the ambitious individuals. (THE SCAB)

Origin
'Battle royal' may refer to a conflict in which many are involved or simply as a general reference to an intense conflict. In the latter case, 'royal' is merely added as an intensifier. Whatever the meaning, there has never been any actual regal involvement implied. The 'royal' is invoked to mean 'a battle fit for a king', as opposed to 'a battle involving a king'. (phrases.org.uk)

mêlée /ˊmeleɪ/ рукопа́шная схва́тка; сва́лка