ALL 'bull' dogs have an ancestry as 'baiting' dogs. ALL-OF-THEM.
Of the various breeds, ==PIT==bulls have the most recent and most intense breeding in that regard. How recent? To the current day.
For most bulldog breeds, you have to go back centuries to find them being widely used for their INTENDED BREED PURPOSE. In the centuries since, few have been used to 'bait' bulls.
With ==PIT==bulls, however, any random dog is almost certainly only a few generations removed from the fighting pit.
Individuals pitbulls might be sweet dogs, but the breed should not exist, and should be made extinct (by ending all breeding of any dog with more than a few percentage points of pitbull ancestry).
(Other bulldog breeds have mellowed a bit over the last couple of centuries, although I don't especially approve of them either, they are no longer the ==PURPOSE BRED THREAT== that pitbulls are).