Simplify the following text for a Grade 8 native English-speaking person.
Original: In 1810 , a princess of Saxe-Hildburghausen , Therese , was married to Crown Prince Ludwig of Bavaria , who became king of Bavaria 15 years later ; this event is the reason for the Oktoberfest , held annually in Munich .
Simplified: In 1810 , a Princess Therese of Saxe-Hildburghausen married Crown Prince Ludwig of Bavaria , who became king of Bavaria 15 years later . The marriage is the reason for the Oktoberfest , held annually in Munich .