He put up his dukes when the argument started.
dukes
idiom Slang
Cockney rhyming slang · East London
fork, i.e. hand, now chiefly when balled into a fist
Origin
via Duke of York
The angry man put up his dukes, but his friend calmed him down before a fight began.
Seeing the aggressive stranger approach, the boxer instinctively put up his dukes to defend himself from the impending confrontation.