Ananda Mahidol Day is observed in Thailand every June 9 to honor the memory of King Ananda Mahidol, the eighth King of Siam, who died on this date in 1946 at the age of 20. The observance was officially adopted by the Thai government in 2015. Ananda Mahidol was born on September 20, 1925, and became king at the age of nine following the abdication of King Prajadhipok. His reign was marked by instability, and he spent much of his childhood and early reign abroad, primarily in Switzerland. His mysterious death in 1946, initially ruled an accident, remains a topic of intrigue in Thailand, with subsequent investigations leading to the execution of his secretary and two aides for murder charges. Ananda Mahidol Day serves as a memorial day, though it is not a public holiday, and it reflects on the legacy and tragic end of a young monarch.