I'd personally go with Merqui Sosa/Prince Charles Williams, off the top of my head. You could cite a fight like Dempsey/Willard, but thats simply one man being brutalized. Doesn't quite compare to two fighters receiving beatings on par/in the neighborhood of Willard's. Really odd fight... A TD after 7 rounds because both men were absorbing so much punishment. More or less they were being watched and everyone was so afraid that someone was going to die/become severely injured in there that they had to stop it. Thats how badly they were going at one another.
Williams/Sosa I was the first one that came to mind when I saw this thread. The rematch was only a half-step down in terms of brutality. Some more: Both Saad/Johnson fights Quiroga/Anifowoshe Alvarado/Wojima Chianoi/Torres I
I thought Sosa was winning the fight though. He took his share of punishment but Williams took the most. Battling Nelson and Ad Wolgast both paid the price for the wars they had.
Corey Sanders/Andrew Golota was very bad. Sander's was beaten so badly he went blind in one eye, really nasty cut in that one too. That was the thing about Golota. He had enough power to ruin your career, but he could never spark a guy out. It was always a prolonged ass kicking, just didn't have that clean, knockout kind of power.
Yeah, I've thought of Escalera ever since as, "The Bayamon Bleeder." However, a case might be made that their rematch which ended when Alex dropped the "Rimini bomb" was more grueling to both combatants. (Arguello said this was the hardest win of his career, and he looked like hell when it was over.) Lee-LoCicero was a spell binding war. My choice would be Manila though, thanks in some measure to referee Padilla forcing Ali to win with punching instead of clinching and mauling. Just a grueling, debilitating war. Milt Bailey said their punches were both reduced to slaps at the end, all the real power in their blows having been exhausted. (Considering the late round power Frazier displayed in the FOTC, and Muhammad against Bonavena, Wepner and later Shavers, this is a frightening thought, to think that each had already absorbed everything the other could deliver in the way of heavyweight power shots, with nothing left in reserve. Ali's hook repeatedly spun Joe's chin as Smoke bored in.)
I think Agrguello vs Escalera II could qualify as well, I just always remember Arthur Mercante saying after the first fight that it was the most brutal match that he ever officiated!
Unbelievable fight. LoCicero's final barrage before Lee puts him down and out makes your hand stand on end. He just unloaded on him up until the stoppage.
Manilla does come to mind as does Ali vs. Frazier I. Not a bloody battle but the wear and tear each fighter absorbed was incredible.
I watched this recently, amazing finish...I didn't know which way it was going to go. Both fighters showed tremendous heart.