King Rama IV Memorial Day is observed in Thailand every October 1, commemorating King Mongkut the Great, the fourth monarch of Siam from the Chakri dynasty. The day is marked by remembrance ceremonies held across the country to honor his contributions to modernizing Thailand and introducing Western innovations. King Mongkut, born on October 18, 1804, became a Buddhist monk before ascending the throne at age 47 in 1851. He sought to establish friendly relations with Western powers to protect Siam from colonization and embraced technological and cultural modernization. Notably, he hired Anna Leonowens to educate his family, an event that inspired the story behind "The King and I." The observance includes a state ceremony, and while it is an official holiday, it is not a non-working day unless it falls on a weekend.