Sohyeon was selected as the crown prince of the Joseon Dynasty in 1625 when his father King Injo took the throne through insurrection in 1623. In 1627, he married a daughter of Gang Seok-gi. During the Second Manchu invasion of Korea in 1636, Sohyeon fled to the Namhan Mountain Fortress with his father King Injo. But when Ganghwa Island was captured by the Manchus, King Injo surrendered to Hong Taiji. Sohyeon voluntarily gave himself up to be a hostage together with his wife and several other Korean officials at Shenyang, the capital of the Qing Dynasty. During his time as a hostage, Prince Sohyeon tirelessly worked as a mediator between Joseon Korea and Qing China. He put much effort into ensuring that Qing would not engage in hostilities against Korea. He protected his people, such as Kim Sang-heon 1570-1652, who was accused by the Manchus of being an anti-Qing agent. Prince Sohyeon also learned the Mongol language and assisted in the conquest of the Western frontier. In 1644, Prince Sohyeon stayed 70 days in Beijing with Dorgon, who had set out to conquer the remnants of the Ming Dynasty. There Prince Sohyeon met Jesuit missionaries such as the German Johann Adam Schall von Bell, and through them he was introduced to Roman Catholicism and Western culture. King Injo and his close administrators condemned Sohyeon's conduct as pro-Qing, and even though Prince Sohyun returned to Korea in 1645, his father King Injo persecuted him for attempting to modernize Korea by bringing in Catholicism and Western science. Prince Sohyeon died suddenly not long after his return to Korea; he was found dead in the King's room, mysteriously bleeding severely from the head. Legends say that Injo killed his own son with an ink slab that the Crown Prince brought from China; however, some historians suggest he was poisoned by the fact that he had black spots all over his body after his death and that his body decomposed rapidly. Many, including his wife, tried to uncover what happened to the Crown Prince, but Injo ordered immediate burial and reduced the grandeur of the practice of Crown Prince's funeral. Prince Sohyeon’s tomb is located in Goyang, Gyeonggi province. King Injo never visited his son's tomb. King Injo appointed Grand Prince Bongrim as new Crown Prince rather than Prince Sohyon's oldest son, Prince Gyeongseon. Soon after, Injo ordered the exile of Prince Sohyun's three sons to Jeju Island, and the execution of Sohyeon's wife, Crown Princess Minhoe, for treason.
