King Sejong

Sejong, the fourth king of the Joseon Dynasty , is a saintly monarch that Koreans are proud of. This drama caters to the psychology of contemporary Koreans who are eager for outstanding idol leaders, telling the story of Sejong's respected life, thereby arousing the historical pride and national self-esteem of contemporary Koreans.
Throughout his life, Sejong was diligent and studious, cared about the people, cherished talents, and always had the dream of "kingly politics" in his heart. He is one of the most respected great men in South Korea. This drama does not stereotype him, but focuses on how he broke through his own limitations and grew into the first politician of the Joseon Dynasty.
The young King Sejong held the political philosophy of "the people are the foundation of the country" and worked hard to learn Confucian classics, mathematics and even foreign languages, armed himself with knowledge, and waited for the opportunity to benefit the people. At that time, he was not yet the crown prince, but he did not covet power. He knew the limits of power, knew how to advance and retreat in the face of justice, and made decisions promptly when necessary. His shining personality set an example for future generations.
Sejong cherishes talents, and the team culture he created is desirable. For the peace of the country and the safety of the people, he always takes the lead, so his ministers obey his orders. However, even if the goals are the same, there are always differences in positions between people. This drama depicts various contradictions, big and small, and also depicts the process of resolving contradictions through democratic discussions.
Under Sejong's diligent governance, Korean society progressed from rule by man to rule by law. During this process, Sejong realized the necessity of educating the people, so he personally organized and created "Hunminjeongeum", leaving a valuable cultural heritage for South Korea.
He was also a king with great international strategic vision. At that time, the safety of the Joseon Dynasty depended on the relationship with the then "hegemonic country" Ming Dynasty. Realizing this, Sejong actively pursued "diplomacy of serving the great power" towards the Ming Dynasty, even despite the opposition of his ministers. Of course, he was not blindly "serving the great power". In view of the national strength of Joseon, he declined the request of the Ming Dynasty to send troops to conquer Mongolia. The autonomy in Sejong's diplomacy will provide a model for thinking and reference for today's South Korea to explore the practical diplomacy path between great powers.
This is a drama with a political theme. It is different from previous palace dramas. In this drama, the palace is no longer a place where concubines compete for favors and love, but has become the political center of the Joseon Dynasty. There, the founding elites of the Joseon Dynasty let their beliefs and passions collide fiercely, performing a series of dazzling political dramas

Episode 1
　　In the palace with the best security in the eight provinces of Joseon, and in the heavily guarded main hall, the body of the official Kim Bian who hanged himself was found! Is there any irreconcilable hatred between Kim Bian and the royal family? Huang Xi and other loyal ministers began to investigate Kim Bian's death with trepidation. At this time, Taizong wanted to personally come to the main hall to confirm Kim Bian's body. Was it a simple suicide? Or was it a plot by the Ming Dynasty envoys who wanted to make Joseon a prince consort? Just when they were at a loss, a sentence slowly appeared on the body: "Are you the one who protects the king?" It seems that the murderer is targeting His Highness... Huang Xi realized that his judgment was wrong and hurried to the East Palace...

Episode 2
　　"Prince Chungnyeong is not the crown prince and can never be king!" Lee Sue told Huang Xi that he was worried about another bloody fight for the throne. Seeing the people cursing Ming envoy Huang Yan, Chungnyeong was torn between ideals and reality...

Episode 3
　　Chungnyeong left the palace and went out into the world to truly interact with the people. After returning, he ignored the dissuasion of others and beat the Shenwen drum for the people to redress their grievances... However, Chungnyeong's simple idea was completely distorted, and the court fell into a weird atmosphere. Chungnyeong believed that even if everyone in the world was distorting his ideas, his parents would definitely understand his thoughts, but in fact, Taejong and Queen Wonkyung were more strict than loving parents. This matter was eventually taken on by Chungnyeong's confidant. Chungnyeong never thought that "death" would break into his life and bring him a burden that he could not bear at such a young age. In the future, will he still care about the people?

Episode 4
　　In order to save Chungnyeong, who was in danger, King Taejong decided to let Crown Prince Yangnyeong abdicate. However, the court officials believed that if Chungnyeong ascended to the throne, the Min family would rule the world, and they opposed the abdication. Someone forged documents to frame Chungnyeong for mocking King Taejong and slandering the Crown Prince...

Episode 5
　　Chungnyeong said nothing and closed his eyes to die. Yangning Prince took back the sword on Chungnyeong's neck and made a shocking decision... Queen Wonkyeong sensed the imminent crisis and asked Taejong to shoot her with an arrow. Taejong realized that the queen knew how to use power just like him, and felt uneasy. At the instigation of Lee Suk-fan, Taejong's beloved concubine Hyobin plotted to change the existing political structure...

Episode 6
　　The first time Chungning met Yoon Hye, the two of them started fighting with fists. At that time, Chungning did not expect that Yoon Hye would be his lifelong friend. Yangning fell in love with Chu Gongzhuang, the concubine of King Jeongjong, who was not disgusted by the concern of the crown prince. Chungning and Hyo-ning were very worried about Yangning. The court finally calmed down. The king summoned the royal family members to a banquet. The princes performed magical archery. The Indeok Palace was brightly lit all night, a scene of peace and prosperity. But in fact, there are still many hidden worries behind the appearance of the new country of Joseon. Taizong received a report of the invasion of Japanese pirates and urgently discussed with the court officials. On the coast of Gangneungpo, the Joseon army was fighting fiercely with the Japanese army. At this time, Yangning single-handedly broke into the Japanese army...

Episode 7
　　The crown prince returned to the court in triumph amid the cheers of the people. Looking at his brother's radiant background, Chungnyeong felt very delicate. Behind the gorgeous victory, the current situation in Gangneungpo is very cruel... Yangning has made outstanding military achievements, but the people have been charred by Yangning's army. Facing the bleeding people, Chungnyeong bit his lips and clenched his fists. Mistakes should be corrected. Chungnyeong hurried back to the palace, but childhood memories came to his mind. Once a prince who is not the crown prince interferes in politics, the price will be extremely heavy. Chungnyeong hesitated. Should he tell the truth or protect the safety of those around him?

Episode 8
　　Choi Moo-sun was the first person in Korean history to make gunpowder. His son Choi Hae-san was kidnapped by Japanese pirates. Chungnyeong strongly suggested to the crown prince that he must find Choi Hae-san immediately, but the crown prince's confidants just whitewashed the situation. The crown prince gave Chungnyeong the opportunity to find Choi Hae-san, but in fact, this was a test for Chungnyeong. Shi-ning wanted to take this opportunity to observe whether Chungnyeong was an enemy or a friend...

Episode 9
　　Taizong arrived outside the East Palace, while Yang Ning and Chu Gongzhuang were inside. The door opened, and a man appeared in front of them...

Episode 10
　　Taizong forcibly implemented the household registration law to distinguish between different identities. Not only the common people, but also the court ministers and Confucian scholars in Sungkyunkwan were very angry about this. The Confucian scholars secretly gathered with Yangning. The head of the internal guard, Jiang Shangren, wanted to expose their treason, but Chungning also participated in the meeting. Joseon's internal affairs were in chaos, and its diplomacy was also facing difficulties. Huang Yan, an envoy of the Ming Dynasty, demanded a large sum of money from Joseon on the pretext of attacking Japan, which angered Yangning...

Episode 11
　　At a grand banquet to welcome the Ming Dynasty eunuch Huang Yan, the crown prince Yang Ning could not suppress his anger and overturned Huang Yan's wine table, which put the diplomatic relations between Joseon and Ming Dynasty into an unprecedented crisis. Huang Xi and other officials tried to appease Huang Yan, but to no avail. Huang Yan even suspected that Joseon and the Japanese pirates were colluding. The evidence was that the documents about the invasion of the Japanese pirates in Gangneungpo recorded that the Japanese pirates invaded without loss. Huang Yan asked Joseon to offer 10,000 horses, send 100,000 troops to the Ming Dynasty, and send the crown prince to the Ming Dynasty. Faced with the endless demands of the Ming Dynasty envoys, Yang Ning incited the Confucian scholars of Sungkyunkwan to demonstrate in front of the Taipingguan. Chungning stopped the demonstration team and proposed to apologize to Huang Yan for the sake of the country and the people, but Chungning's voice was drowned out by the cheers of support for Yang Ning. Chungning returned home, and Yi Huai pointed out to him: The crown prince was wrong, but Chungning's approach was also incorrect.

Episode 12
　　The crown prince Yangning was exiled to the Jongmyo, but the Confucian scholars and young officials of Sungkyunkwan still supported the crown prince. They wore mourning clothes to protest the trampling of Joseon's self-esteem, but the inner guards arrested them all and put them in prison. There was also public resentment in front of the Taipingguan, and Taizong personally came to stabilize the people's hearts... The court was at a loss as to how to restore relations with the Ming Dynasty. Under such circumstances, the officials focused their energy on catching the traitor who leaked the documents of the Japanese pirates' invasion of Gangneungpo. The most suspicious people were the eunuchs who were sent to the Ming Dynasty and returned to the country. In order to find out the traitors, the eunuchs were tortured, but suddenly the king ordered them to sneak into the Taipingguan with Yin Huai and others...

Episode 13
　　The Confucian scholars were still dissatisfied with the court's attitude and prepared to submit another petition. Taizong ordered a resolute suppression of the Confucian scholars. Lipan Huang Xi submitted a petition to stop it. King Dingzong convened a meeting of clan members in a side hall and believed that the exile of the crown prince should be ended and sent to the Ming Dynasty as a hostage. At this time, Prince Hyo-nyeong took the initiative to stand up and said that he was willing to be a hostage. Huang Yan promised to give Taizong two months, but secretly wrote a letter back to the Ming Dynasty, advocating an attack on Joseon, which was learned by Yin Huai and others. Prince Chungnyeong reported the contents of the secret letter to Taizong, but was questioned by Taizong about his motives...

Episode 14
　　Yoon-hye stops the plot to poison Hwang Yeon. After failing to poison, Queen Min investigates Yoon-hye's identity and learns that he is Chungnyeong's man. Taejong ends the exile of the crown prince. The crown prince decides to go to the Ming Dynasty as a hostage. The court officials begin to discuss who is suitable to be the crown prince after the crown prince. The intelligence agent sent by Hwang Hee to Liaodong obtains intelligence that will help him take the initiative in the negotiations. The key now is to bring Hwang Yeon back to the negotiation table. Can Chungnyeong, who is suspected by his father and mother of being greedy for power, really become friends with Hwang Yeon?

Episode 15
　　The forces of the resurrected Goryeo were active near the capital, and Taizong was furious and ordered that the main culprit must be found at all costs. Wang An confessed under torture who the main culprit was. Negotiations were reopened in Taipingguan. Huang Yan was kidnapped at night, but he kept silent about it the next day, saying that he went out for a walk at night. The Ming Dynasty advocated that Korea pay tribute of 10,000 horses, send 100,000 soldiers, and send the crown prince as a hostage. Huang Xi did not want to increase the burden on the people, and resolutely agreed to pay tribute of only 500 horses, which made Huang Yan very unhappy...

Episode 16
　　Huang Yan mentioned the prince who could replace the crown prince. Although his words were brief, they were meaningful and caused a huge stir in the Joseon court. Chungnyeong let out the anger that had been pent up in his heart. Facing Chungnyeong who was confronting him head-on, Yangning was at a loss. In order to form a new force around Chungnyeong, Zhao Mosheng and others kept going to Chungnyeong's father-in-law Shen Wen. In the meantime, Jingning watched this political struggle with a detached attitude, waiting for an opportunity to act. Taizong revealed to Queen Wonjing his reluctance as a father hidden deep in his heart, and Wonjing was shocked. Faced with this tragic fate of the royal family that even her own son could not be trusted, Queen Wonjing could only sigh...

Episode 17
　　Taizong asked Chungnyeong, who was silent, a question he didn't want to ask: Do you want to be the crown prince? Faced with Taizong's unconventional approach, Yangning and Chungnyeong expressed their respective opinions, and their views seriously conflicted. In the drastic political environment, Zhao Mosheng and others found Chungnyeong's father-in-law Shen Wen to ensure Chungnyeong's safety and asked him to send troops to protect Chungnyeong. Li Shufan, the military minister who held military power, kept his troops on hold and watched the political situation change. The excited Yangning sought a way to get past Taizong, and Queen Wonkyung wanted her son, who disagreed with her, to change his mind. After thinking hard, Taizong issued an ultimatum to Yangning.

Episode 18
　　Chungnyeong earnestly asks for forgiveness from King Jeongjong on behalf of Yangning, whose relationship with Chu Gongjong was discovered. Unexpectedly, Hyoning proposes to expose Yangning's crime to King Taejong, and King Jeongjong is undecided. Finally, King Jeongjong goes to the palace where King Taejong is... Queen Wonkyeong wants Hyobin's son Kyungning to marry Cha Yeon, and Hyobin holds a grudge and begins to take revenge on Min. In front of King Taejong, who is expressionless, Yangning can't answer anything...

Episode 19
　　Yangning's relationship with King Jeongjong's concubine Chu Gongzhuang shocked the loyalists such as Jo Mo-sang, but Park Eun realized that he could use Yangning's story to attack his political enemy He Lun, so he wanted to find Chu Gongzhuang first more than anyone else. In order to save Yangning, Yangning's two uncles strongly advocated finding Chu Gongzhuang and executing her. In the chaos, Lee Soo persuaded Chungnyeong to make a decision early, and Chungnyeong's heart began to waver...

Episode 20
　　The whereabouts of Chungnyeong the Great is unknown, and Shen Wen and others are restless. In order to prevent Jingning and Cha Yan's wedding, Xiaobin gave a dangerous secret order to Niu Er Nainai. Queen Yuanjing put pressure on Shen Wen and asked Chungnyeong to stay at home no matter what. Chungnyeong was extremely tough in front of Queen Yuanjing, and Yuanjing was at a loss. Seeing her son's growth but not happy, Queen Yuanjing felt painful...

Episode 21
　　Even the leader of the Crown Prince faction, He Lun, recognized Chungnyeong's leadership ability. He Lun personally came forward to make a deal with Chungnyeong, and wanted to promote Chungnyeong to become the Crown Prince on the condition that he would not be held accountable for his own corruption. What would be the result of the encounter between Chungnyeong, who has a simple political philosophy, and the political old fox He Lun? Yangning regards Huang Xi as a political mentor, and Huang Xi is also willing to actively help the Crown Prince because of the resurrection of Goryeo to ensure that the regime is not affected. Under the guidance of Huang Xi, Yangning described a decent policy direction. Taizong was very satisfied with this. But someone is destroying the smooth sailing of the Crown Prince: Xiaobin has mastered the old things that are enough to threaten the political life of the Central Queen Min; Park Eun brought up the Chu Palace Makeup incident again, hoping to overthrow the Crown Prince and He Lun in one fell swoop. Quan Yizhi was instructed by Yuhuan to find Chu Palace Makeup and assassinate Chungnyeong, but his actions were noticed by Yan Zizhi, who handed him over to Chungnyeong...

Episode 22
　　The spring paintings of the Crown Prince and Chu Gongzhuang were posted throughout the city, and the court debated the authenticity of the paintings. If the paintings were true, then the Crown Prince would not have the moral qualifications to inherit the throne. Unlike low-level officials who valued the Crown Prince's morality, senior officials such as Park Eun were calculating who would benefit from the Crown Prince's scandal. In order to protect the Crown Prince, Huang Xi covered up the key points of the incident and began to investigate who was framing the royal family. He finally confronted Yuhuan, the leader of the Goryeo Resurrection Force. Surrounding the Crown Prince's scandal, everyone was looking for Chu Gongzhuang, and Taizong asked Chungnyeong to hand over Chu Gongzhuang. Chungnyeong was therefore in a fierce confrontation with Taizong. He wanted to rescue Chu Gongzhuang and save the political life of the Crown Prince Yangning. Finally, Chungnyeong made a major decision...

Episode 23
　　In order to protect Chu Gongzhuang, the gentle and smart Shen bravely dealt with the chief of the inner guard. Taizong announced that he would find out the truth about the Yangning scandal, and the low-level officials cheered. Chu Gongzhuang was finally interrogated, and the presiding judge Park Eun pushed all the blame on Chu Gongzhuang. Chu Gongzhuang lied that the prince knew nothing about everything and cleared the prince. Finally, the prince and Chu Gongzhuang, who was about to become a political victim, looked each other in the eye. Will he tell the truth? In the fight between He Lun and Park Eun, Taizong stood on Park Eun's side, but He Lun would not give up easily. He made the last decision for his political life. Chungnyeong was wandering in the political whirlpool. At this time, the humble girl Ershan appeared in front of Chungnyeong...

Episode 24
　　He Lun clearly announced that he regarded Chungning as the future king. Although Chungning was very angry about this blatant expression, he actually had very complicated feelings. Taizong banned Yangning from participating in the military conference, but ordered other princes to perform at the conference. The real battle for the throne showed signs. Chungning disobeyed orders and did not attend. Yin Huai believed that Chungning did this because he was worried about Yangning, but the monk Li Xiu did not think so. He said that Chungning did not think he was sure to win against Yangning. Yangning disobeyed Taizong's order to play a banned game. Yuhuan's vixen-like mermaid Li concealed her true identity and approached Yangning. Shen gave birth, and Chungning went to visit with gifts for the child. At this time, Yuhuan and others attacked Chungning...

Episode 25
　　Chungning was seriously injured, and Shen, who was weak after giving birth, took care of her husband regardless of everything. Under Shen's care, Chungning survived the crisis. But something went wrong with the child. Chungning asked for an investigation into the truth of the assassination attempt on him. Yuhuan urgently eliminated the spy planted in the Military Affairs Bureau and tried to cover up the truth. However, these did not escape the eyes of two people, namely Choi Hae-san, the most famous firearms expert in North Korea, and the girl Ershan. The two rescued Chungning that day. Based on the clues provided by the two, after investigation, Chungning met the killer under Yuhuan

Episode 26
　　Chungnyeong wanted to cut off Jang Yeong-sil's hand, but Lee Sue stopped him with tears. Yoon Hye also thought that if Jang Yeong-sil was executed, the crime of assassinating Prince Chungnyeong would fall on the crown prince and the Min family, so he stepped forward to stop Chungnyeong. So Chungnyeong proposed to make a deal with Yeong-sil. The person Jang Yeong-sil drew was Jeon Haeong-soo. The court began to attack the base of the Goryeo revival forces, but the leader of the Panjun, Ok-hwan, had already gone into hiding, and Jeon Haeong-soo was captured by the government troops. The crown prince asked Ning (Yangning) to suggest to Taejong that the descendants of the Goryeo royal family who had changed their surnames to Ok, Jeon, and Tian should be captured, and a tough countermeasure should be taken against the rebels. But Chungnyeong strongly opposed it. He believed that the reason these people were still obsessed with Goryeo was because they did not realize the legitimacy of Joseon. Chungnyeong went to the prison to visit Jeon Haeong-soo...

Episode 27
　　Taejong took a tough stance against the resurgent forces of Goryeo and executed those who surrendered one by one. This move caused a strong counterattack from Yuhuan, and the capital was full of spies who wanted to take Taejong's head. In addition, the Ming envoys had arrived in Yizhou, and the court was under pressure to deal with the rebellion before the envoys arrived. Taejong gave Park Eun a knife and asked him to execute the rebels on a large scale. Many people were not rebels, but they were going to be executed just because they had dealt with the rebels. Chungnyeong could no longer sit idly by and sent people to negotiate with Yuhuan, who also accepted the negotiation plan. Chungnyeong went to the hiding place of Yuhuan and others alone...

Episode 28
　　Chungnyeong met the rebel leader alone and was questioned about the crime of being taken hostage and disturbing the court. Taejong punished Chungnyeong to personally execute the rebel general Jeon Haengsu. However, Chungnyeong was unable to raise the sword to execute the executioner at the execution ground. At this moment, the judge rescued Jeon Haengsu. Taejong asked Chungnyeong why he did not execute the rebel leader. Chungnyeong replied that if Joseon could not reflect on its past mistakes and was essentially a country that suppressed the people, then he would rather not be a prince of this country. Taejong angrily sent Chungnyeong to the north. The rebels announced that they would launch an attack the day before the military exercise. It was unpredictable whether they would target the military exercise ground or the palace, so the court strengthened its vigilance. At this time, the bodies killed by the rebels were found in the palace. Huang Xihe asked Chungnyeong to investigate whether there was a secret passage for the rebels in the palace...

Episode 29
　　The rebels began to attack the palace. Some of them attacked Gwanghwamun, while the main rebels tried to enter the palace through the secret passage. However, under Huang Xi's layout, the rebels suffered a fatal blow in the secret passage. Another group of rebels approached the side hall where Taizong was. It turned out that there was more than one secret passage. At this time, Chungnyeong returned to the palace and confronted the rebels... In the Geunjeong Hall, Taizong announced that due to health reasons, he would hand over all government affairs except for employment, diplomacy, and military affairs to Rangning...

Episode 30
　　The Crown Prince Rangning wants to build a large-scale position in the north. Min Wuxiu secretly calls Li Qian, who is about to go to the north, and gives him another task, which is to monitor Chungning and prevent him from threatening the position of the Crown Prince. The Crown Prince is preparing to conquer Liaodong. The Min brothers suggest that a large amount of funds can be obtained by promoting the privatization of land currently only implemented in Gyeonggi Province to the whole country, but this move has caused heated debate among court officials. Rangning also expelled Jingning, the son of Hyobin, whom he disliked, from the palace. Hyobin cried and reported this to Taizong, but to no avail. Hyobin is increasingly hating Rangning and the Min family, and is planning a conspiracy to change the political situation

Episode 31
　　The wet nurse admitted that it was the Queen who instigated the murder of Gyeongnyeong. Taejong could not help but feel angry at the Queen's actions. The Queen said that she could not stand the betrayal. The Crown Prince Rangnyeong took the initiative to release his uncles Min Wusu and Min Wuhui who were imprisoned in the Yijinfu. For this reason, some low-level officials were dissatisfied with the Crown Prince. In order not to implicate the Queen and the Crown Prince, Min Wusu applied to return to prison. Hyobin attacked the people around Rangnyeong. Rangnyeong could not bear it anymore and went to Taejong to warn Hyobin. Huang Xi wanted to stop Rangnyeong's reckless behavior, but Rangnyeong would not listen at all. Finally, there was a voice among the ministers to abolish the Queen's position, and Taejong was forced to make a decision.

Episode 32
　　The Yijinbu asked the Min brothers to prove that the crime had nothing to do with Rangnying, but the Min brothers refused. Rangnying was betrayed by his uncles and felt that nothing could be done according to his will. He once again fiercely opposed the court officials on the land privatization plan. Rangnying announced that officials who violated his orders would be dismissed, and some low-level officials began to miss Chungnyeong. Li Qian was sent to prepare for the crown prince's expedition to Liaodong. He did not understand the way that the governor of the capital, Cui Runde, had a good relationship with the Jurchens for the sake of peace in the north. The conflict between the two became deeper and deeper, and finally Rangnying dismissed Cui Runde from his post. The Jurchens announced an attack on Joseon.

Episode 33
　　The Jurchen attack caused great suffering to the people on the Joseon border. Choi Yoon-deok would rather lose his position than abandon the people, which touched Rang-deok. The troops sent by the crown prince were the real cause of the Jurchen attack, but Li Qian used this to seek credit and reward from the court. The court praised the crown prince for sending troops to consolidate the border and discussed whether to send troops to conquer the Jurchens immediately, but some people questioned whether the crown prince was using the name of consolidating the border to conquer the Jurchens. Taizong called Jingning and asked him to go to Jingcheng to find out about Choi Yoon-deok and sent an investigator to Jingcheng. The crown prince wanted to appoint a confidant to the position, but Yoo Jung-hyeon volunteered to go, so Rangning began to try to cover up his mistakes...

Episode 34
　　The truth was revealed. Li Qian's crime was to faithfully carry out Rangnying's orders. Liu Tingxian asked Chungnyeong, what kind of punishment should the crown prince receive for this matter? Huang Xi learned that the crown prince sent troops to the north to prepare for the expedition to Liaodong, and advised the crown prince to admit his mistakes in order to be forgiven, otherwise the truth would be revealed to the world when Liu Tingxian returned to the court. Someone found Chungnyeong's father-in-law Shen Wen and proposed to push Chungnyeong to the position of crown prince, on the condition that he would disclose his identity...

Episode 35
　　The Crown Prince took advantage of the absence of King Taejong and the Queen to lead his army to Gyeongseong. The Crown Prince's pro-Crown sent a lie to the court officials that the Crown Prince was out hunting. The court officials were very dissatisfied with the Crown Prince's choice to go hunting when the King was not in the capital. Park Eun persuaded Sim On to ask Chungnyeong to return to the capital, but Sim On was hesitant. Yoon Hye also persuaded Chungnyeong to return to the capital with him, but Chungnyeong refused. In fact, the reason why Chungnyeong refused to come back was that he was not sure he could do better than the Crown Prince, and he told Yoo Jung-hyeon about his thoughts. Huang Xi learned that the Crown Prince led the central army to Gyeongseong, and finally went to persuade the Crown Prince

Episode 36
　　In Gyeongseong, Hamgil Province, Chungnyeong led the central army to stop the crown prince, Yangning. Yangning was furious and shouted at Chungnyeong, asking him to get out of the way if he didn't want to be a traitor. Chungnyeong did not show any weakness and pointed out that Yangning was committing treason at this moment. If he did not lead the army back, the position of the crown prince might not be saved. Yangning led the army back to the capital, and what awaited him was the cold reaction of the court officials and the memorials demanding the punishment of the crown prince. Taizong never said a word about this matter. He was waiting for the crown prince to reflect. But Yangning not only did not reflect on himself, but also claimed that if Chungnyeong had not stopped him, he would have successfully expanded the territory of Korea. Prime Minister Liu Junghyeon risked his life to advise Taizong: The crown prince should be selected from the wise regardless of age. But who can be considered a wise man? The court officials had different opinions. Taizong asked Chungnyeong, who had returned to the capital, whether he intended to be the crown prince...

Episode 37
　　Chungnyeong answered Taejong that he had been trying to become a wise man. In response, Min asked him if he had decided to regard his own brother as a political enemy? Chungnyeong said he was mentally prepared. Chungnyeong's firm statement was beyond everyone's expectations. The news quickly spread outside the palace, and the expectations for the new prince across the country became higher and higher. But Taejong could not make a decision easily. He ordered Rangning to personally execute his confidants, reflect deeply, and reform himself. The heart of the monarch is unpredictable, and the court officials are worried. At this time, King Jeongjong was determined to promote Hyo-nying as the new prince, because it was known to everyone in the world that Rangning had no qualifications to be the prince, and Chungnyeong had denied the legitimacy of the founding of the Joseon Dynasty and was considered a sinner. Only Hyo-nying was the most suitable. And at the time of chaos, rumors of unknown origin once again shrouded the court...

Episode 38
　　Hyo-nyeong brought Yu-ri into the palace and asked Taejong to depose the crown prince and establish Yu-ri. The crown prince's behavior was heard by the court officials, and the idea of ​​deposing the crown prince gradually prevailed, but Taejong was still unable to make a decision and was troubled by it. King Jeongjong, who supported Hyo-nyeong, insisted that Chungnyeong's previous denial of Joseon's legitimacy was a big problem, and if Chungnyeong was to be the crown prince, he must be tested again. So Taejong presided over a "thought test meeting" attended by all the court officials. Chungnyeong still believes that the bloodshed and sacrifice in the rise of Joseon was wrong. Yoon-hye reminded Chungnyeong that it was important to control the political power, and Chungnyeong fell into deep thought...

Episode 39
　　Chungnyeong was appointed as the crown prince, but what lay before him was rampant Japanese pirates, severe drought, and the people's miserable lives. In order to understand the people's sentiments, Chungnyeong personally went on a private visit in disguise. The people blamed all the misfortunes on the replacement of the crown prince. In addition, Park Eun, who was appointed as the crown prince's teacher, was very dissatisfied with Chungnyeong's non-attendance of lectures and his blind private visits. Park Eun advocated that Chungnyeong preside over the rain-praying ceremony to win over the people, but Chungnyeong believed that if the rain-praying ceremony did not bring rain, it would add fuel to the fire. The crown prince was in a serious political crisis. Shen Wen proposed a general amnesty to stabilize the people's hearts, but the important ministers disagreed. The crown prince planned to go on a hunger strike to share the joys and sorrows with the people...

Episode 40
　　Taizong suddenly announced that he would abdicate to the crown prince Chungnyeong. Chungnyeong led the ministers to persuade Taizong to take back the order, but Taizong was firm in his attitude. He convinced the ministers that the former king still held the royal power before the new king turned 30, so there was no need to worry. Should a puppet king be established? Chungnyeong's father-in-law Shen Wen expressed this concern to Taizong as Shen's father, and proposed that since he abdicated, the new king should be given enough authority, otherwise no minister would serve the new king wholeheartedly. Taizong ignored Shen Wen's remarks and held a grand enthronement ceremony for the new king Sejong. As soon as the enthronement ceremony ended, Taizong planned the battle to conquer Tsushima Island and instructed Sejong to levy special taxes in preparation for war. However, Sejong believed that the time was not yet ripe for the conquest of Tsushima Island and hoped to resolve the issue through diplomatic means...

Episode 41
　　Taizong ordered Yin Huai to cultivate a detailed understanding of the people, things and things on Tsushima Island, so-called "knowing yourself and the enemy, you will win every battle." At this time, Tsushima Island sent an envoy to visit, but he did not meet Sejong first, but went directly to see Taizong. The court ministers were divided and discussed. To make matters worse, the Ming Dynasty envoys came to visit at this time and strongly protested, believing that the replacement of the crown prince had not been approved by the Ming Dynasty, so the Ming Dynasty could not recognize Sejong's identity. Under the lobbying of the Joseon ministers, the Ming Dynasty envoys hinted that it was not impossible to solve it if there were generous gifts, but Shen Wen said that Sejong had just ascended the throne, and it was not a good start to offer tribute to the other party in the first step of diplomacy. King Taizong told Sejong that it would be better to let Shen Wen appoint the prime minister and solve the problem of the Ming Dynasty envoys by the way. This made Sejong question the deep meaning of King Taizong, who always hated foreign relatives interfering in politics. But Shen Wen said that he was willing to go through fire and water for Sejong, and asked not to doubt the deep meaning of King Taizong. These words moved Sejong to tears.

Episode 42
　　History repeats itself, and King Taejong wants Sejong's politics to start with the purge and execution of his subjects. So Taejong appoints Park Eun to torture and put the blame on Sim On. The criminal can't stand the torture and says that Sim On is the criminal with a rebellious heart. But the loyal Kang Sang-in never succumbs to the torture. Queen Soheon asks Sejong to save her innocent father. Although Sejong is heartbroken, he can't comfort her. Sejong comes to King Taejong's place and tells him that he wants to protect his subjects. But Taejong says that he must make his subjects obey absolutely, and this is the only way and the way he can teach Sejong. Kang Sang-in was executed by being torn into pieces by five horses.

Episode 43
　　Taejong ordered the arrest of Shen Wen, who had gone to negotiate with the Ming Dynasty, upon his return, and ordered Sejong to use the seal. Queen Soheon asked Sejong to demote her to a commoner, so that her father would not be a relative and could be spared from death. Ershan, who was standing aside, looked at the ministers who were forcing Sejong and the queen with hatred. Ershan asked Queen Soheon to go to the Ming Dynasty to find the prime minister and told the prime minister not to return to Joseon, otherwise his life would be in danger. However, Shen Wen said that he was an envoy appointed by His Highness and had to return to Joseon to report to His Highness, even if this was his last mission, he had to complete it. The court ministers asked Sejong to demote Queen Soheon to a commoner.

Episode 44
　　Sejong: "Now I really understand my father, the father who was the most straightforward in front of power, the father who did not want to share power even between father and son, so I really understand my father who exiled the late king, your father, to Hamheung." Sejong: "Father-in-law, the prime minister, can be sacrificed, but father, you must promise me that you can no longer purge like this. Besides, I can't give up my wife." In order to prevent Queen Soheon from being deposed, Taejong asked Sejong to take in eight concubines at a time. Sejong: "Even so, I don't want to lose you. Are you willing to trust me again?" Queen Soheon: "I don't want to trust you anymore." Queen Soheon left. Shen Wen: "If he doesn't abandon me, I will end my own life. It must not be easy for him to make this decision. If he doesn't abandon me, more ministers will die, so he must have made this decision with blood and tears. For the sake of your highness and Yuanzi, you must return to the palace. Don't blame yourself for not being able to protect your father, let your father go in peace!" Queen Soheon: "Father!!" Queen Soheon cried in her father's arms. Shen Wen, the prime minister of the government, was sentenced to death.

Episode 45
　　Tsushima Island took the initiative to attack the naval base of Joseon. King Taejong ordered the destruction of all the Japanese colonies, and would rather kill a hundred people by mistake than let one go. King Taejong: "War is a reality. You must first consider the situation that countless soldiers will die in battle. It is a terrible reality." King Sejong: "Then why don't you learn from the enemy. They can find out the largest naval base of Joseon. But we are unwilling to investigate the enemy carefully. Solving disputes without war and relying on diplomacy should be the first choice of military strategists. This is my unchanging belief. But if the expedition is inevitable, I will not object. However, I am against the expedition without any intelligence. Because I think war is not a simple game of victory or defeat between the two sides, it is a matter of life and death." There is also strong support from the Japanese pirates behind the Tsushima Island incident. After King Sejong failed to seek diplomatic means, King Taejong ordered the expedition to Tsushima Island. The first expedition in Joseon history - the expedition to Tsushima Island, kicked off.

Episode 46
　　King Taejong and King Sejong held a prayer ceremony for the army to go to war, and the enemy also sent assassins to assassinate King Taejong and King Sejong. At this time, the people of Dongnae Waguan in Gyeongsang Province spread rumors that someone in the royal family was injured and that a national mourning might be declared. The enemy thought that this was a good opportunity to attack Joseon. On the other hand, King Sejong was receiving envoys from Kyushu. On June 20, 1419, the first step of the expedition to Tsushima Island, the Battle of Dojipo, was an absolute victory under the planning of Joseon. It was a tough punishment for the Japanese pirates who had invaded and plundered the entire lower three provinces, including Chungcheong, Jeolla, and Gyeongsang, and Hwanghae Province from time to time since the end of Goryeo to the beginning of Joseon. However, the number of casualties of the Japanese army was surprisingly small, which can be said to be a war of careful killing of the enemy. But this was just the beginning.

Episode 47
　　After successfully rescuing the captured Joseon and Ming prisoners, Jiang Yingshi also used gunpowder to blow open the prison door and successfully rescued Ming Dynasty Hanlin scholar Lu Jin. Lu Jin looked at the big hole in the door in surprise. At this time, the enemy army turned back and pursued them, and the Joseon army once again used gunpowder to get rid of the pursuers. This was the biggest victory in this Battle of Tsushima. Ershan saw that Sejong had not rested well since the war began. Ershan persuaded Queen Soheon to go see Sejong, but Queen Soheon still left silently.

Episode 48
　　Because the enemy attacked the Joseon army at night, the death and injury of Joseon reached more than 200 people. Some soldiers proposed to attack the enemy camp immediately. At this time, Yin Huai came to the camp with the royal order and conveyed the intention to negotiate with the owner of Tsushima Island. Sejong proposed to Taizong to make peace with Tsushima Island. Sejong said that this war has had a serious impact on the livelihood of Joseon people. If it continues, the subsequent impact will be uncontrollable. Therefore, diplomacy is the best policy to incorporate Tsushima Island. The owner of Tsushima Island finally surrendered to Joseon. Not by force but by diplomacy to bring it under the influence of Joseon, this is the greatest significance of the Tsushima expedition. Because of the severe drought, Sejong ordered the production of a large number of water wheels throughout Joseon to relieve the drought. Ershan sent cold drinks to His Highness and the scholars of Jixian Hall in the name of Queen Soheon, and Sejong came to the Central Palace to express his gratitude. Han Shanggong outside heard it and reprimanded Ershan.

Episode 49
　　Mountain torrents and surging rivers flooded many rice fields and caused many casualties. The ministers did not discuss disaster relief methods first, but tortured the officials of the Guantianjian. Zhao Mosheng even pointed out that it was the king's immorality that caused the anger of heaven and punished the world. Sejong's face was solemn. Zhao Mosheng said that Sejong should go to Zhaoge Office to worship heaven and ask heaven to calm down. However, Sejong said that praying to heaven would not help with disaster relief, and it would be more helpful to use manpower for disaster relief. The whole country, even the royal family, was preparing for the day of the eclipse. Everyone held their breath and waited for the arrival of the solar eclipse. Because the solar eclipse had not occurred for a long time, just when everyone was talking about it because the monarch had no virtue, the solar eclipse began.

Episode 50
　　The court ministers pointed their spearheads at Prince Hyo-nyeong, and wanted to use Sejong's hand to deal with Prince Hyo-nyeong, which would become a political burden for Sejong. How should Sejong choose between Prince Hyo-nyeong and Jihyeonjeon? In the second year of Sejong's reign, Joseon developed a new generation of movable type printing, "Gengzizi", which was the first step in the advent of the Sejong era, which opened up a brilliant culture.

Episode 51
　　The ministers of the court thought that Sejong's handling of politics in Jiheonjeon was the so-called "secret room politics" so they all wanted to eradicate Jiheonjeon. And Park Eun was the person in charge of Jiheonjeon. So the ministers wrote to Sejong, hoping that Sejong could stop Hyo-nyeong's heart to Buddhism and "respect Confucianism and suppress Buddhism", close the temple and dismiss Park Eun, so that they would no longer demand the abolition of Jiheonjeon, otherwise the ministers would resign collectively. Jiang Yingshi thought it was too strange that the weather forecast would be inaccurate, so he buried his head in research and finally found out that it turned out that Joseon used the calendar of the Ming Dynasty, and the Ming Dynasty and Joseon were in different places, so of course the astronomy should be different. Queen Won-kyeong was taking care of the flood victims in the temple with Hyo-nyeong and Queen Soheon, and because Sejong ordered the closure of the temple and Hyo-nyeong, after reprimanding Sejong, she fainted in a moment of anger. After being diagnosed by the royal doctor, it was confirmed that Queen Won-kyeong had malaria. Regardless of his own safety and everyone's objections, Sejong insisted on entering the hospital and taking Queen Wonkyung out for treatment.

Episode 52
　　King Sejong ignored the law and carried Queen Wong Gyeong to Inwangsa Temple for treatment. A group of people in the temple begged King Sejong to let them hang lanterns and pray for the Queen Dowager. Seeing the sincere prayers, King Sejong couldn't help but ask, "What have you taken away from the people because of the coercion of the ministers and my concessions!?" The ministers were divided into two factions because of the Buddha worship, and King Sejong issued a wonderful decree to the ministers of both factions. Queen Won Gyeong passed away peacefully in the arms of King Taejong.

Episode 53
　　King Taejong taught the crown prince how to be a monarch by learning archery. King Sejong ordered his trusted ministers to secretly research Joseon's own calendar. Cho Mo-sung gathered the ministers to discuss countermeasures after learning about it. The ministers believed that if Joseon's calendar was researched, it would mean breaking off diplomatic relations with the Ming Dynasty, which could cause disputes or even lead to war.

Episode 54
　　Jo Mo-saeng actually told Hwang Hee that for the sake of Joseon, another monarch should be chosen! ! After the King knew Jo Mo-saeng's intention, he ordered Park Seok to kill Jo Mo-saeng, charging him with "treason". Unexpectedly, the six departments united to rebel against the King and Sejong. Taejong: "I actually trained Jo Mo-saeng and the entire military department to become the enemy of my son!!" Sejong went to Hwang Hee after getting drunk: "It's worse to be a bystander than to oppose." After the King stepped in and said something, Hwang Hee went to the palace to meet Sejong.

Episode 55
　　Under Hwang Hee's active lobbying, most of the lower-level officials returned to their posts. Hwang Hee also used a trick to force Li Pan to return to his original position. Because Cho Mo-sang used the name of Rang Ning Dae-gun as a call to abolish the current King Sejong, Rang Ning Dae-gun came forward. Rang Ning Dae-gun said to Cho Mo-sang: "You want to make me the Supreme again, right? Okay, let's go to hell together." "This is a serious crime of treason. At this point, if you still refuse to admit defeat, the scholars outside Jixian Hall will not only report it to the Sixianfu and Sijianyuan, but also post a notice in the eight provinces of Joseon to inform the world." Queen Soheon looked at Sejong with slumped shoulders with heartache: "Your Highness has to bear the state and family affairs on his shoulders, and I, his wife, can't even give him a little warmth." Queen Soheon shed tears. The King and Sejong had their first and last deep conversation. The king passed away peacefully while he was looking kindly at the crown prince practicing archery

Episode 56
　　During the reign of King Taejong, Hwang Hee used his power to seize Park Bao's wife. The documents that Taejong ordered to be hidden were used by the ministers of Cho Mo-sung's faction to attack Hwang Hee. Zheng Linzhi, a scholar of Jixian Hall, was the first to discover this. He was in a dilemma! He wanted to keep Hwang Hee to help King Sejong, but his conscience was not right. After King Sejong knew about it, he gave the decision to Zheng Linzhi. At the meeting, Hwang Hee admitted everything himself.

Episode 57
　　When the atmosphere was condensed in the air, Park Bao's wife appeared and explained that the situation at that time was not as described in the document, and that Lord Huang Xi was slandered. Jiang Yingshi came to the Ming Dynasty to learn the calendar because of his order, and met Dayan again in the palace of the Ming Dynasty.

Episode 58
　　Jiang Yingshi sneaked into the Ming Dynasty's Imperial Observatory and prepared to steal technology. At this time, Hai Shou, an official of the Ming Dynasty, learned of Jiang Yingshi's purpose and prepared to arrest him. Jiang Yingshi returned to Joseon safely and prepared to start creating "Joseon's sky". Queen Soheon and Princess Jeongso went to see their mother who was demoted to a maidservant. Queen Soheon was heartbroken. Queen Soheon's mother scolded him for visiting her because she was just a maidservant.

Episode 59
　　Sejong wanted to confer the title of fifth-rank official to Jiang Yingshi, but the court officials objected, saying that there was a difference between the noble and the humble, and how could a slave be conferred the title of fifth-rank official? But Sejong thought that as long as he had talent, there was nothing wrong with that! But even the scholars in Jixian Hall jumped out to oppose it. The ministers held a joint protest to oppose it, and Sejong decided to fight them with a hunger strike!

Episode 60
　　In the heavy rain, Sejong insisted on protecting Jiang Yingshi. And the number of ministers supporting Sejong gradually increased. Jeongso, who had agreed with Sejong to go on a tour incognito, fell seriously ill after waiting in the rain all night. Huang Xi got the handle of Zhao Mosheng and handed it to Sejong, but Sejong told Huang Xi that he did not want to easily abandon Zhao Mosheng, who had outstanding abilities. Huang Xi smiled after leaving the hall. Because of this, Jiang Yingshi successfully put on official uniforms. The sick Jeongso asked Sejong to pardon her grandmother who was an official maid. Sejong was embarrassed.

Episode 61
　　The construction of Cheonyi Terrace was in full swing. At this time, the envoys of the Ming Dynasty came to Korea. They suspected that Korea had some unknown movements and asked to visit Gyeongbokgung Palace. Princess Jeongsoo fainted again after being seriously ill. Queen Soheon still could not forgive Sejong, and even the air was so solemn. Han Shanggong, who was standing by, said to Sejong that if the grievances of Buwongun could be cleared and the wife of the palace could no longer be an official maid, the princess's heart disease and body would be cured. The imperial physician said that the princess suffered from hesitant anemia, which was a very serious disease. Sejong was furious after hearing this. The envoys of the Ming Dynasty and the city of Beijing in the Ming Dynasty both took extraordinary actions. Jeongsoo, who was devastated by the disease, handed the hands of her father and mother to each other, and asked them not to let go of each other's hands in the future, and then fell into Sejong's arms and left. She left the world at such a young age.

Episode 62
　　Scholars from Jixian Hall, Sixianfu, and Sijianyuan launched a petition to overturn the case of the late Shim On. Because they believed that people like Zhao Mosheng had no right to stay in the court. The court fell into chaos again. Queen Soheon issued an imperial decree: "As the queen mother of Joseon, I, Consort Gong, do not want to overturn the case of Shim On, who is both my father and the former Prime Minister. I also think that punishing the relevant responsible persons is not a desirable behavior, and advise everyone to immediately stop all debates on this matter. I hope that all ministers will not take the queen mother's request lightly." Queen Soheon also summoned the Prime Minister and asked him to assist the master well. She will protect the adults' families well, because she knows the pain of a traitor in the family. The Prime Minister had a very complicated mood when he walked out of the Junggung Palace. Then, he handed in his resignation letter and he would take full responsibility for the case of Shim On. Sejong and Queen Soheon came to Shim On's tomb. Queen Soheon said, "If you want to cry occasionally, you can come to the Junggung Palace. Please don't ask your children to wipe your tears anymore. That's why your daughter says you are a crybaby. You have been living too lonely for a long time, and as the queen mother, I am the most compassionate to the people, but have I not taken care of you for too long? This is what I have been thinking about. Now please don't suffer alone. I should share your fatigue and pain. I want to accept all this as my destiny." The two hugged each other and cried.

Episode 63
　　Li Sui, who went to the border of Korea with Zhao Mosheng, saw the Jurchens who fled across the river to Korea and thought that they should be taken in and naturalized, but Zhao Mosheng and the local people thought that they were just barbarians and could not be taken in. When the news came back to Korea, even Sejong agreed with Li Sui's opinion, but the court ministers disagreed. Even King Gyeongnyeong disagreed. The emperor of the Ming Dynasty passed away, and the ministers of the Ming Dynasty prepared to bury Dayan with him so that she could serve the emperor forever. Jiang Yingshi, who came to the Ming Dynasty, was very sad when he heard the news. Looking at the towering palace walls, Jiang Yingshi could not save his beloved, so he could only set off fireworks to send his beloved off. Dayan looked at the fireworks outside the window and left with a smile and tears...

Episode 64
　　There were many explosions in the capital, and there were leaflets saying "We want a monarch who is a pure Korean people, not a barbarian king". Gyeongnyeong and Cho Mo-saeng caused civil unrest, and they wanted to take advantage of the situation to establish a new monarch. Han Shanggong reported to Queen Soheon that Sejong's political enemy Cho Mo-saeng had been meeting with Gyeongnyeong recently. Queen Soheon summoned Gyeongnyeong's mother, Hyobin, to the palace.

Episode 65
　　One of the people involved in the arson incident was one of the children that Sejong had taken care of when he was exiled to Mirror City. She broke into the palace and presented a painting to Sejong, which depicted the people being displaced and inhumane because of the tax system and the oppression of the people by the literati. Sejong was shocked after reading it and felt sorry for the people. Looking at those people, Sejong knelt on the ground and called himself a sinner

Episode 66
　　Sejong announced at court that he would reform the tax system to restrain the literati, which triggered protests from literati across the country. At this time, Zhao Mosheng thought that the time to change the new master was getting closer. Zhao Mosheng was secretly taken to a place, and when he lifted his hood, he was shocked to see the person who came. Sejong ordered Zhao Mosheng to cancel the secret order of rebellion, and he quietly erased the matter. Zhao Mosheng asked: "Is this because you want to protect King Daejun?" Sejong sentenced Zhao Mosheng to be exiled to a distant place. Sejong: "My brother's mother is also my mother." Hyobin: "Our King Ning really has a good brother! As a mother, I will dedicate all my tears in my life to you. You are a monarch who cares about the people as much as you love your brothers. As a mother, I will pray for your health with tears in my life, Your Highness!"

Episode 67
　　The Crown Prince was about to hold a wedding ceremony for the Crown Prince's Consort, but the Crown Prince disappeared. The new Crown Prince's Consort was a woman who dared to express herself and was not bound by etiquette. This gave the wedding ceremony a different atmosphere. Sejong had always been pursuing a policy of submission, which made the Ming Dynasty and the Jurchens quite dissatisfied. People from the Ming Dynasty's East Factory contacted Zhao Mosheng, hoping to win him over.

Episode 68
　　The crown prince came to the border of Ming Dynasty, but was stopped by soldiers and could not enter Ming Dynasty. The leader of the East Factory of Ming Dynasty told the crown prince that the emperor of Ming Dynasty refused the crown prince to see him. The crown prince interrupted the order of King Sejong to build a city on the border, and asked the highest commander of the local area to return to the capital with him. This was the first time that the crown prince rebelled against King Sejong. Queen Soheon asked the crown prince not to see her again until the matter was settled. King Sejong: "I hope that Joseon will become a Joseon that will not succumb to the power of Ming Dynasty. Therefore, we will start with the construction of a defense system along the river line. We will expand the territory of Joseon to Liaodong line. No matter how difficult it is, even if I can't see the results in my life, I will thoroughly implement this policy. I hope that the ministers will stop opposing it." Li Sui was ordered by King Sejong to find the boundary marker. After going through mountains and rivers, he finally found the boundary. Li Sui: "The border of Goryeo (the border of Goryeo is said to be on the boundary monument of Gonggan Town) - 700 miles north of the Tuman River, Gonggan Town of Shanchun Ridge, this is the northernmost border of the Joseon Kingdom. A new era will begin in the future."

Episode 69
　　Li Sui asked his followers to defend the boundary monument and the future of Joseon, while he set out on the road back to the capital alone. Wang Zhen, the leader of the East Factory of the Ming Dynasty, ordered assassins to kill Li Sui! ! Li Sui, who was designed to drink poisoned wine, refused to tell the location of the boundary monument until his death. He dragged his poisoned body back to Joseon with his last breath and met Sejong. Gongganzhen-This is one of the nine northeastern provinces opened up by Yun Gwan during the reign of King Yejong of Goryeo. The "Geography of Sejong's Annals" records that its location is 700 miles north of the Tuman River. Thirty years after the founding of the country, Joseon at that time had not yet restored its stable border line bounded by the Yalu River and the Tuman River. The boundary monument of Gongganzhen will be the cornerstone of the consolidation of the four counties and six towns established by Sejong, and it is also a symbol of Sejong's earnest wish to expand Joseon's territory to the north and hope that Joseon will take off.

Episode 70
　　Sejong thoroughly investigated the territory of Joseon, including even uninhabited islands. The New Geography of Eight Provinces was a huge declaration by Sejong that he would not neglect every inch of the territory to establish Joseon's territorial rights. The development of the national defense line centered on Gyeongwon and Luyeon and bounded by the Tuman River and the Yalu River was the process of concretizing this declaration. During the test firing of gunpowder, Jiang Yingshi was accidentally burned by the gunpowder that exploded due to an accident. The crown prince opposed the development of new weapons because he opposed war. However, the crown prince's teacher Shen Zhang said to the crown prince, "Is your father a person who wants war? I believe you know the answer, don't you?" The Jurchens led by the chief of the Jurchen tribe attacked Luyeon, not only brutally killing more than 50 people but also capturing more than 100 people. Sejong's anger reached its peak. In order to protect the safety of the people, he ordered a powerful attack on the enemy's base in the name of Joseon. In order to stop Korea from expanding its military, the Ming Dynasty ordered Korea to pay tribute of 10,000 cattle. Korea's response was to use ginseng instead of 10,000 cattle. Wang Zhen refused outright. But Yin Huai showed the evidence that Dongchang had killed Li Sui and asked Wang Zhen to return to the Ming Dynasty to settle the tribute issue and relax the strict restrictions on the import and export of gunpowder imposed by the Ming Dynasty on Korea. Wang Zhen was speechless.

Episode 71
　　While Wang Zhen was appeasing and perfunctory about Joseon's demands, he sent people to unite with the Jurchens to deal with Joseon. Zhao Mosheng captured the son of the leader of the Jurchen Odorli tribe to threaten the leader Tong Mengge, telling him not to unite with other Jurchen tribes to attack Joseon, otherwise his son's life would be in danger. The prince's teacher Shen Qiang died of overwork, so the prince advised Sejong to stop the expedition to open up territory. Because Sejong's eye disease and wind disease had worsened due to excessive fatigue in recent days, the imperial physician suggested that he rest for a while. So Sejong went on a hot spring trip (a royal trip for recuperation). So the palace announced to the outside world that all palace affairs would be temporarily handled by the prince. The Jurchens thought this was a good opportunity to capture Luyan. In fact, Sejong's people secretly appeared in Jiangjie. Sejong told the soldiers who were about to go on the expedition to return safely. In the 15th year of Sejong's reign, the first Joseon campaign against the Jurchens at Poju River began.

Episode 72
　　The Battle of the Baju River laid a good foundation for the subsequent Northern Expedition. During the reign of King Sejong, Korea experienced a 15-year-long punitive war, with the military defense line of the Yalu and Tuman Rivers as the center, expanding the territory of Korea to the north. All this was achieved by King Sejong's unyielding belief in not giving up an inch of land, his ministers and generals who fought to the death for this belief, and the precious results of the blood and lives of many unknown soldiers. The palace was in a very tense atmosphere. The Crown Princess often stayed alone with the palace maids in a room. This matter was heard by Queen Soheon, who was shocked. In the 16th year of King Sejong, Korea finally made a Jianyitai, and measured the North Pole (latitude) of Seoul through Jianyi, and everyone on the scene was excited. The Wuwei Army (a secret spy organization under the Korean internal guards) officially began to deal with the East Factory of the Ming Dynasty.

Episode 73
　　Dongchang sent assassins to assassinate Huang Zan, the Ming envoy who was visiting Joseon, and wanted to put the blame on Joseon. Fortunately, Joseon had the foresight to send people to rescue Huang Zan. Huang Zan was about to arrive, and Sejong ordered people to destroy the documents for making new weapons to prevent them from being discovered by the Ming Dynasty. Jiang Yingshi asked the princes to recite these documents so that they could be destroyed. After knowing this, the prince also participated in the recitation. In Jiang Yingshi's eyes, he thought that the prince was also trying to agree with Sejong's policy. The automatic timekeeping device in Seoul surprised the visiting envoys.

Episode 74
　　Choi Wan-ri handed over the document of Joseon's production of new weapons to Huang Chan, which was actually just a blank sheet of paper. He also said that with the national strength of the Ming Dynasty, it should be possible to fill in the blank sheet of paper with the content of making new weapons. Moreover, how could he have such a document with his authority! This made the Ming Dynasty's intention to buy Choi Wan-ri fail. The prince privately investigated the mistakes of Sejong's governance, and the prince also asked Sejong to visit incognito. Let Sejong go to the people to see the mistakes of governance in person. The prince told Queen Soheon that he was not opposing for the sake of opposition, but to prepare to be