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.