Korean Royalty. Born the second son of King Yongjo of the Choson Dynasty and his concubine Lady Sönhui some seven years after his elder brother, Crown Prince Hyojong died in 1728. At three months, the new prince was moved into the Chosung-jon Mansion, the traditional palace of the Crown Prince. An apparent prodigy, the prince was reported as walking at four months, and by two, he could write about sixty Chinese characters. Apparently, the king wished to been seen as the most Confucian of rulers, and his son's personality did not lend itself to such a discipline. An estrangement between father and son grew. On April 27, 1744 Sado married eight year old Lady Hyegyong. Over the winter of 1745, Sado fell seriously ill with an unnamed malady. Sado celebrated his coming-of-age on March 10, 1749. Five days later, he began married life with his princess, and a son was born the following year. A second son, Prince Chöngjo, was born in 1752, the same year Sado fell ill during a measles epidemic. The illness apparently exacerbated some abnormal behaviors the prince had suffered since his lengthy illness of seven years before. He began suffering from delusions and nightmares; in the summer of 1756 the prince began acting violently toward his servants. He became ill with smallpox that winter, and though he recovered, the Queen and Queen Dowager died the spring of 1757. These events apparently worsened the prince's derangement. He beat his eunuchs, raped court ladies he could not seduce, and finally began killing household servants as the mood took him. In January 1761, Sado mortally injured his own concubine and he stalked his sister, Hwawan. He began wearing disguises and wandering about Seoul incognito. He then began killing people at random; fortune tellers; royal physicians, translators, and court workmen all died at his hands; tThe court lived in terror of the prince. In June 1762, King Yongjo received a letter from one of his ministers, informing him of the gross misconduct of the Crown Prince, and Yongjo finally decided that Prince Sado was too dangerous to be allowed to live. The King ordered court eunuchs to fetch a large rice chest, and the prince was ordered into it. The lid was then nailed shut and Sado was left to die. After eight days, the prince was dead. Sado's eunuchs, court guards, workmen and shamans were put to death as well. His wife was demoted to commoner status and returned to her family home. His unfortunate sister, Princess Hwawan was demoted, sent into exile and then poisoned. In 1776, Prince Sado's second son ascended the Phoenix Throne as King Chöngjo, as soon as he took the throne, he purged all those he held responsible for his father's death. He honored his father as if he had been a reigning monarch. Sado's grave site is now a UNESCO World Heritage Site.