What has to be remembered, is that the English Bulldog of the day, bore little resemblance to what we now associate & accept as that breed. In fact the French Bulldog bears a greater similarity, to what was originally deemed to be the English Bulldog of the 1800s.
That the Lace workers of Nottingham took their Toy Bulldogs to Normandy, France, is an historical fact. Without any breed club to watch over them & many Toy Bulldogs being pets without papers, breeding was not accurately recorded & without doubt not all matings were to other toy Bulldogs.
These were the origins of the French Bulldog. Initially based on chance, little interest being shown towards them by the French, with no person from that country coming forward with knowledge of that formative period.
They did not become popular until the Coquette went crazy over them. With this notoriety it then became daring & risqué for fashionable ladies to have them as companions.
Visitors from America were attracted to this totally different little dog & they must be credited for developing & fixing a lot of the characteristics we today associate with being a typical French Bulldog. While the English tried to use imported stock to rekindle the Toy English Bulldog, the Americans developed a new breed fixing traits such as the BAT EARS, which are today such a feature of the breed.
The French deserve recognition in the title of the breed because that was the country of inception.
So it can be seen that France, England & America have contributed most to the establishment of the breed. It is just unfortunate that cooperation between those countries could not establish a Universal standard for the French Bulldog.
Peculiarly distinctive features of the French Bulldog are the bat ear, which are found in no other dog. For many variations to the original toy bulldog, including the Fawn with Black mask colour, I would suggest you look towards the Pug as a contributor.