Ruling with an iron fist, Injo's lust for power ultimately led to his ascension to the throne after a rebellion
The eldest son of Prince Jung-won who was the fifth son of King Seonjo, Injo led an uprising (反正) that resulted in him becoming the 16th Joseon king. He was involved in more plots than any other king in Joseon history. Ten years before the uprising he created, Gwanghae had taken control of the throne, a rumor that went "Saemundong, where Prince Jungwon resides, has an aura of royalty (王氣)" began to spread throughout the capital. The West faction decided to choose Prince Jung-won's third son, Prince Neungchang to be the next king if their plot to overthrow the sitting king succeeded.
However, the plot was detected and Prince Neungchang was executed for his involvement. Prince Jungwon died soon after from the loss of his son. Meanwhile, Prince Neungyang wept openly in Gwanghwamun Square despite the danger of his actions. His crying was not meant to show his mourning for his dead brother, but an act to promote himself to the people.
When powerful men plotting to overthrow the king came to his family home, Prince Neungyang believed they were going to choose him to be their king. But they chose his brother instead, which left Prince Neungyang feeling dejected and humiliated.
It was Prince Neungyang who leaked the details of the plot and the identities of the plotters to the government. If his brother had become the next king, he knew he would be eliminated. Power cannot be shared and his actions were justified in that it was to ensure his survival.
After his public display of feigning mourning, Prince Neungyang became a frontrunner to be the next king and he rounded support from the West Faction, which did not know of his betrayal. But there was one obstacle in his path. It was Prince Jungmyung. She held great sway in public opinion. Prince Neungyang was furious whenever people talked about Jungmyung in lofty tones but he hid his anger. Since she was a princess, she could never become a king. But Princess Jungmyung was not following his plans. She would not resign herself to staying quite in the Gyubang as she spoke frequently with the ministers and politicians to voice her opinions that garnered support. This hurt Prince Neungyang's pride and fueled his inferiority issues. So he decided to get rid of Princess Jungmyung...
