From the link here we find some background and information about Octoberfest and how it got started.
Crown Prince Ludwig, later to become King Ludwig I, was married to Princess Therese of Saxony-Hildburghausen on 12th October 1810. The citizens of Munich were invited to attend the festivities held on the fields in front of the city gates to celebrate the happy royal event. The fields have been named Theresienwiese (“Theresa’s fields”) in honor of the Crown Princess ever since, although the locals have since abbreviated the name simply to the “Wies’n”.
Horse races in the presence of the Royal Family marked the close of the event that was celebrated as a festival for the whole of Bavaria. The decision to repeat the horse races in the subsequent year gave rise to the tradition of the Oktoberfest.



