In 1810 some bier loving German royalty decided to get married (Crown Prince Ludwig and Princess Theresia of Bavaria if you really must know). It was their very successful 16 day celebration starting in late September and continuing on through October that later became the annual event known as Oktoberfest in Munich, Germany.
Octoberfest in America
Beer drinking Americans tend to celebrate Octoberfest only when prompted by marketing & advertising by big-label bottlers... and we tend to prefer the "c" spelling variation.
The 2018 festival begins September 22nd and goes until October 7th. Check out some Oktoberfest Biers you can buy here in the U.S. for your own tent party... Oh, and don't forget the big-ass pretzels.