The game that we know today as "blackjack" has also been known as "Vingt-un," which is derived from the French word for "Twenty-One" and this has also been anglicized to "Van John." In Spanish that would be "Veintiuna," which is how Miguel de Cervantes (famous as the author of "Don Quixote," referred to it in at least one of his novellas. Although it is not known exactly when or where the game might have started, it can be stated with relative certainty that the game has been in existence for over 400 years. Evidence also exists that there was a 17th-century game called "bone Ace" in which the ace could be given the value of either one or 11; the rules were similar to Vingt-un, so it's quite likely that it was part of the evolution of the game toward what we know today.
The early versions of Blackjack , or 21 as it was called at the time, were generally known to be banked by the player, and casinos of the time simply accommodated the players with tables, while they paid a "rake" to the house. The games were popular, because they contained an element of skill, and certainly it interested players that they could actually have some say in their own fate. Even so, the player was largely flying in the dark; Vingt-un did not allow the player to see the dealer's up-card when making decisions, and the dealer was not required to play by strict rules in the casino.
As the game started to develop in the United States, the rules evolved to the point where the player could see an up-card, and the dealer was required to hit on all 16's and stand on all 17's. That made things more plausible for the player.
The game rightfully carried the label of "caveat emptor" in many venues in which it was played. Gambling was allowed in some jurisdictions such as Louisiana, as well as some territories that were more or less unregulated, or where the law was murky. Eventually it was played in clandestine fashion in a number of locales around the country, like Saratoga Springs, N.Y., Hot Springs, Ark. or Hallandale, Florida, dependent upon the "cooperation" of local law enforcement. When Nevada legalized gambling for good in 1931, it became a game that was house-banked there, and has remained so ever since.
As well as it can be documented, the name "Blackjack" is one that was coined in the United States, and finds its origin not just through the name of the hand that pays off with a two-card 21, and even more specifically one that paid off with an ace of spades and a Jack of either clubs or hearts; in other words, a "black jack." This was a bonus offered in many casinos, and it paid off at 10-to-1 odds.
It is quite probable that there were players who knew correct Basic Strategy and even card counting, in one form or another, as far back as the 1930's. There are stories, however - one of them surrounded a man known simply as "Greasy John," who got that name because he would customarily sit in front of the dealer with a big bucket of fried chicken and eat for hours on end, winning consistently while he was doing it.
Most gambling historians theorize that these players were keeping track of tens or aces, or both, using some methodology that was most comfortable to them. They never revealed their systems in public, through print or otherwise, however, so there is little to go on in that regard. Of course, it was understandable; casinos were, for the most part, "rough" joints, and players who followed a mathematical system may have been considered cheaters.
As a result, the world was deprived of any details regarding scientific findings on the game until 1956. That was when a group of four employees at the Army's Aberdeen Proving Grounds - who have since become known as the "Four Horsemen" - went public with the first known strategy for attacking the game of blackjack.
And the flood gates opened.