almost right

The signal for death was a thumbs up with the fist placed against the chest, various methods were used to spare a gladiators life but the most common was either to wave a white handkerchief or to signal with thumb hidden or thumb down,which indicated to put the sword away or stick it in the ground respectively.

glad. didn't fight to death

the gladiator arena is not like THUNDERDOME (2 men enter, 1 man leaves). For the fighters, like in the movie, they were treated to fine lives (yes, some were slaves). Others lead meager lives, but they were treated like boxers or wrestlers; they were known to fight many battles. Think about this: if every time there was a fight, one man must die, they would drop the population of gladiators by 1/2 for every full round. This has been proven.

For comment 13195

Your half right, some Gladiator combats weren't to the death, and most of them weren't major battles as shown in the movie either. But you should do some reading up on Gladiator history, initially, most Gladiator combats were simply aimed at injuring the enemy sufficently, then the battle was over. But after the Republic fell and the Roman Empire came to being. 'To the death' battles became dominant a few years after the birth of Christ. The battles were none too frequent either, your typical Gladiator fought, at most, about 3 times a year, so if you want to be precise, only a few hundred Gladiators could have died in any given year... Unless of course, there was a combat festival like the kind shown in the movie (they were infrequent, but they did exist), that's when Gladiators start to die in big numbers, there was one combat festival in Ancient Rome in which 5,000 Gladitors died, but that is the exception and not the rule.