When the Japanese forced the Gwangmu Emperor, Gojong, to abdicate his throne in 1907, they enthroned his oldest living son (actually the fourth-born) as the new Yunghui Emperor. The new emperor, Sunjong, was also the son of the Empress Myeongseong, who had been assassinated by Japanese agents when her son was 21 years old.
Sunjong ruled for just three years. In August of 1910, Japan formally annexed the Korean peninsula and abolished the puppet Korean Empire.
The former emperor Sunjong and his wife, Empress Sunjeong, lived the rest of their lives virtually imprisoned in Changdeokgung Palace in Seoul. Sunjong died in 1926; he had no children.
Sunjong was the last ruler of Korea who descended from the Joseon Dynasty, which had ruled over Korea since 1392. When he was dethroned in 1910, it ended a run of more than 500 years under the same family.