While the most varied theories exist about the the exact origin of the French Bulldog, the most prevalent opinion is that it originates from the miniature or toy bulldog brought to France by the Nottingham lace workers during the industrial revolution and economic crisis in England.
Speculations about a more ancient origin mention artwork and skeletal finds of the ancient Indian dog, known as the Chincha Bulldog, which lived in ancient Peru and resembles the French Bulldog to a striking degree.
Excavations of the burial grounds of Ancon in central Peru of mumified bodies of dogs, skulls and skeletons indeed confirmed that bulldog-like dogs lived in Peru from 1100 to 1400 AD. In 1937 Professor Richard N. Wagner and Max Hilzheimer studied Peruvian mumified dogs and excavated skeletons.  

The Nottingham lacemakers were welcomed with open arms by the French to the coastal towns of Normandy and in particular to Brittany and Calais where the old traditional work continued.
Why precisely these smaller bulldogs became very popular amongst the workers in the Nottingham lace industry in the first place is not very clear but speculations are that these little bulldogs were in fact "culls" of the established Bulldog Breeders in England, who were generally more than happy to sell these undersized examples of their breed to fanciers of the "new" Toy breed in England. 

This was especially true of the "tulip" eared puppies that cropped up at times in Bulldog litters. And later on when they had to move to France, the pocket-sized edition of the bulldog was very convenient because they were easier to smuggle aboard ship and keep out of sight during the trip to France and because they were more prone to adapt to the new living conditions.
In the farming communities north of France where they moved to, the little Bulldogs became very popular as ratters and loyal family companions and their population soon grew. In the 1860s the export of miniature or toy bulldogs from England to France was so great that they practically became extinct in England.
The miniature small bulldog is thought to have been crossed with the native "terrier boule" ( not to be confused with the Bull Terrier), also called "ratier" (as it was used to chase rats) owned by butchers and other meat trade workers in the abbatoir areas in the suburubs of Paris, De Villette and Pantin, which looked like a terrier or small bulldog and eventually giving rise to the French Bulldog.  

Other breed historians claim they were also crossed with the pug but lack of records has so far frustrated researchers to establish the breed's exact genealogy.
A little later the coach drivers, shoemakers and street traders and even the police became fans of the "petite Boule". It soon became the star of working class Parisian society.
Its physique, small size, peculiar physiognomy and enchanting personality made it the darling of fanciers of flatfaced dogs. As the new, smaller Bulldogs gained popularity in France, they became favourites of the Parisian "Belles De Nuit" ("Ladies of the Night"), the courtesans, who kept it for its excentric appearance.
It was during this period that the upper classes, through their coachmen and bordellos, began to discover and fall under the charm of this small dog with its persuasive and at times disturbing look. The aura of notoriety that ownership of the little dogs conveyed soon read more