battle royal

a fight in which more than two combatants are engaged.

a heated argument: After a while the discussion turned into a battle royal.

Origin of battle royal

First recorded in 1665–75

Then there would have been a battle-royal that had set the earth quaking.

Plays--First Series |August Strindberg
So this battle-royal in art commenced and raged with virulence.

Great Musical Composers |George T. Ferris
This record on one occasion depicted a battle-royal at breakfast, "over the marmalade," Sally said.

Somehow Good |William de Morgan
Then stood forth the Tinman in his ire, and a battle-royal commenced.

Blackwood's Edinburgh Magazine, Volume 69, No. 425, March, 1851 |Various

Who knows had there been a battle-royal, and was Miss Newcome having her wounds dressed upstairs?

The Newcomes |William Makepeace Thackeray

battle royal

a fight, esp with fists or cudgels, involving more than two combatants; melee

a long violent argument