Last official bare knuckle title fight

Jack Kilrain is perhaps best known for challenging champion John L. Sullivan in 1889 in the last world heavyweight championship prizefight decided with bare knuckles under London Prize Ring rules in history.

They fought 1-minute rounds with 50 seconds break between the rounds.

In a hard-fought contest, Kilrain lost at the start of the 76th round (after 2 hours 16 minutes) when Mike Donovan, his second, threw in the sponge. Kilrain had not wanted to give up thinking that he could outlast Sullivan, but Donovan defended his actions insisting that Kilrain would have died had the fight gone on.

In any case, the Kilrain-Sullivan fight can rightly be listed among the greatest fights of the pre-modern era.