At the dawn of the 19th century, the Roman Catholic Church under Pope Pius the 7th decided to crack down on the ever-increasing rumored threat of vampires (although the scientific community wouldn't formally recognize vampirism as fact until the early 20th century, and the US Legal system wouldn't recognize them as citizens until 1993) as well as Napoleon's moves to take most of Europe with both labeled as the 'despoilers of the church', unifying most all major European countries save for France on June 10th of 1809, also known as the Day of Cleansing (known to vampire culture as 'The Inferno'). Before that, even the best revealing of the nature of vampires, less than a century before, was still commonly doubted and shrouded in rumor.
After the pogrom that lasted at least a fortnight (although the term 'Day' stayed in the history books), the only organized groups of European vampires were to be found in France (leading to rumors of the French Aristocracy being a rampant haven for vampires both before and after the edict from Pius VII, rulers of France dallying with a Belle vampire mistress, and the guillotine being made necessary due to the frequency of those to be executed being technically already dead). Fear of a second Day of Cleansing is what has lead to a large number of vampires migrating from Europe to America, where vampires have formal legal protection. Never the less, the Parisian Vampire Council has continued to meet in (what is now) the Musee Carnavalet since the mid 1500s.