pit bull

The ancestors of modern pit bulls come from the bulldogs and terriers of England. At one time every county in England had its own breed of terrier. Many of these still exist; however, some have evolved into new ones. Such is the case for the English White and the Black and Tan terriers, whose descendants include the bull-and-terriers, the Fox Terrier, and the Manchester Terrier. Terriers served an important purpose in England by killing Vermin that might otherwise ruin crops, damage property, or spread disease such as the Black Plague. The development of sports such as rat- or badger- baiting further added to the breeds' importance.
Mastiff type dogs also have a long history in England; they are thought to have been brought by the Celts. It is also known that the Normans introduced the Alaunt. These dogs were used in battle and for guarding, but they also served utilitarian purposes, such as farm work. Specifically, these dogs accompanied farmers into the fields to assist with bringing bulls in for breeding, castration, or slaughter. The dogs, known generally as bulldogs, protected the farmer by subduing the bull if it attempted to gore him. Typically a dog would do this by biting the bull on the nose and holding on until the bull submitted. Bulldogs were bred to have powerful, muscular bodies and the resolve to hold onto a violently struggling bull despite injury. These traits permitted the development and rise of the bloody sports of bull-baiting and bear-baiting. In Elizabethan England, these spectacles were popular forms of entertainment. However, in 1835, bull-baiting and bear-baiting were abolished by Parliament as cruel, and the custom died out over the following years.
The sport of dog fighting, which could be carried out under clandestine measures, blossomed. Since Bulldogs proved too ponderous and uninterested in dog fighting, the Bulldogs were crossed to English White and Black and Tan Terriers. They were also bred to be intelligent and level-headed during fights and remain non-aggressive toward their handlers. Part of the standard for organized dog-fighting required that the match referee who is unacquainted with the dog be able to enter the ring, pick up a dog while it was engaged in a fight, and get the respective owner to carry it out of the ring without being bitten. Dogs that bit the referee were culled.
As a result, Victorian fighting dogs (Staffordshire Bull Terriers and, though less commonly used as fighters, English Bull Terriers) generally had stable temperaments and were commonly kept in the home by the gambling men who owned them.
During the mid-1800s, immigration to the United States from Ireland and England brought an influx of these dogs to America, mainly to Boston, where they were bred to be larger and stockier, working as farm dogs in the West as much as fighting dogs in the cities. The resulting breed, also called the American Pit Bull Terrier, became known as an "all-American" dog. Pit bull type dogs became popular as family pets for citizens who were not involved in dog-fighting or farming. In the early 1900s they began to appear in films, one of the more famous examples being Pete the Pup from the Our Gang shorts (later known as The Little Rascals).
During World War I the breed's widespread popularity led to its being featured on pro-American propaganda posters.