Crown Prince Sado

Crown Prince Sado (Korean: 사도세자; Hanja: 思悼世子; 13 February 1735 – 12 July 1762), personal name Yi Seon (이선; 李愃), was the second son of King Yeongjo of Joseon. His biological mother was Royal Noble Consort Yeong of the Jeonui Yi clan. Due to the prior death of Sado's older half-brother, Crown Prince Hyojang, the new prince was the probable future monarch. However, at the age of 27, he died, most likely of dehydration and possibly of starvation after being confined in a rice chest on the orders of his father in the heat of summer.

Lady Hyegyŏng, Sado's wife, wrote a memoir in 1805 detailing their life together. She records that the prince suffered a severe illness in 1745, during which he often lost consciousness. Although he recovered, the tense relationship between Sado and his father King Yeongjo led to him experiencing severe anxiety whenever in his father's presence. When Sado came of age at 15, his father appointed him regent, giving him the power to make decisions on administrative matters. Yeongjo wanted Sado to have an experience of ruling the country. At the same time, Yeongjo wanted stronger power. During Sado's regency, the dispute between Soron and Noron became stronger, much to Yeongjo's disappointment. Lady Hyegyŏng describes King Yeongjo as perpetually dissatisfied with whichever course of action Sado chose. Yeongjo also did not permit Sado to visit the ancestral tombs until as late as 1756, nor was he allowed to attend auspicious court events. Yeongjo also always made sure to chastise his son in front of a large crowd, either of ladies-in-waiting or eunuchs. As a result, Sado formed a strong bond with his sister Princess Hwahyeop, who was similarly disfavoured by their father. When she died in 1752, Sado was reported to have grieved intensely.

In 1752, Sado read a Taoist text called Okchugyeong (옥추경; 玉樞經). Whilst reading, he hallucinated that he saw the Thunder God. Henceforth, he was terrified of thunder and refused to touch any object engraved with the characters of the book.

Sado took a secondary consort, Yang-je (Royal Noble Consort Suk), with whom he had a son in 1754. Terrified of his father's anger, Sado forced her to take abortive medicines, but still, the child was born safely. Arrangements for the delivery and housing were made by Lady Hyegyŏng.

In 1757, King Yeongjo's adoptive mother (Queen Inwon) and wife (Queen Jeongseong) died within a month of each other. Sado had been close to both of them and their deaths led to a marked deterioration in his mental health and relationship with his father. As a way of dealing with his frustration and rage, Sado beat his eunuchs. In the same month as the burial of Queen Jeongseong, Sado walked into his chambers holding the severed head of a eunuch whom he had killed, forcing the ladies-in-waiting and his wife to view it. After this, he frequently killed palace staff to release his emotions, as well as assaulting and raping many ladies-in-waiting. Lady Hyegyŏng reported Sado's issues to his mother Royal Noble Consort Yeong, but begged her not to speak to anyone about the matter, as she feared for her safety if Sado discovered she had told someone. By 1758, a previous phobia of Sado's regarding clothing (vestiphobia) became intensely problematic.

For him to get dressed, I had to have ten, twenty, or even thirty sets of clothes laid out. He would then burn some, supposedly on behalf of some ghost or other. Even after this, if he managed to get into a suit of clothes without incident, one had to count it as great good luck. If, however, those serving him were to make the slightest error, he would not be able to put his clothes on, no matter how hard he tried. In the process, people were hurt, even killed. It was truly dreadful.

— Lady Hyegyŏng,

Late in 1757, Sado took another secondary consort, Park Bing-ae (Royal Noble Consort Gyeong), who had been a lady-in-waiting to his grandmother, so his relations with her were considered to breach the incest taboo. When Yeongjo found out, he berated his son and Sado eventually jumped down a well to attempt drowning himself, but a guard pulled him out. Lady Hyegyŏng had, by this point, managed to have Bing-ae hidden in the home of Sado's sister, Princess Hwawan.