After the Northern Expedition, Emperor Taizong has been unhappy and depressed. He indulged in alcohol all day long, and did not care about the government. Every night, he often had nightmares and entanglements, and his body deteriorated day by day, and suddenly he died one day, and the dynasty was full of color.

Before, Emperor Taizong had already appointed Zhao Dechang as the crown prince. It stands to reason that after the death of Emperor Taizong, Zhao Dechang could have ascended the throne and inherited the ceremony. However, in the imperial court, there have always been turbulent and treacherous, and nothing can be taken for granted.

At this time, Wang Jien began to make waves again. Wang Jien and Zhao Dechang have long had a rift, and he was afraid that the crown prince would be greatly disadvantageous to him after he succeeded to the throne, so he had evil intentions. Empress Li also disliked Zhao Dechang, and had already intended to abolish the establishment, but Wang Jienyan didn't know about it. As early as when Emperor Taizong was ill, Wang Jien had already gathered a large group of people and began to bewitch Empress Li. Queen Li is worried that she has no companion, and it is difficult to sing alone. It's like a person is sleeping, and someone happens to bring a pillow, of course Queen Li is overjoyed when she hears this. Wang Jien and Empress Li immediately conspired, and they deliberately set up another crown prince so that they could succeed to the throne as they thought fit.

After the death of Emperor Taizong, Wang Jien and Empress Li conspired again. After the plan was decided, Wang Jien personally went to summon Prime Minister Lu Duan. Fortunately, Lu Duan was thoughtful and noticed the change.

Lu Duan knows Wang Jien's behavior very well, and knows that he is very scheming, and he is even better at speculation. At the beginning, when Emperor Taizu was seriously ill and dying, the queen urgently ordered Wang Jien to summon Zhao Defang into the palace, but he secretly took the edict and went to Zhao Guangyi, the king of Jin. Later, Zhao Guangyi was the emperor, and he was Emperor Taizong. Many people discussed it privately, guessing that Zhao Guangyi must have committed the suspicious case of plotting to usurp the throne with the matter of "axe sound and candle shadow".

Just a few days ago, Emperor Taizong's condition suddenly worsened, and Lu Duan entered the palace to ask about his illness. At this time, Emperor Taizong was already in danger, and Lu Duan entered the palace, but he did not see the prince Zhao Dechang accompanying him. The only people who served by Emperor Taizong's side were Wang Jien and Empress Li, and Lu Duan was very worried when he saw this. He knew that Wang Jien was accustomed to intrigue and trickery, and he was worried that he would play some tricks that would be unfavorable to the prince. Lu Duan came out of the palace and hurried back to the Prime Minister's Mansion. He immediately wrote a secret letter and asked his confidant to give it to the crown prince Zhao Dechang. In the letter, Lu Duan urged Zhao Dechang to enter the palace as soon as possible in case of accidents.

Today, Wang Jien was ordered by Empress Li to summon himself. Hearing that Wang Jien reported that Emperor Taizong had died, Lu Duan couldn't help but be shocked. Seeing that Wang Jien had no sadness, he actually had a commanding and invincible look in front of him. Lu Duan knew that something was wrong, and he was afraid that it would cause trouble, so he was busy calming down and thinking about countermeasures. Lu Duan knew that there was no further ado, so he immediately made a decision, first took the words to stabilize Wang Jien, and then withdrew from the pavilion and locked Wang Jien in the painting pavilion of Zhongshu Province with his backhand. trapped Wang Jien, in order to prevent accidents, Lu Duan arranged for people to strictly guard him, and he rushed to the court.

Seeing Empress Li, Empress Li said to Lu Duan slowly, "Now, the emperor is no longer there, and it stands to reason that the crown prince was appointed so that he could inherit the throne." This is also a reasonable and logical thing to do. In the prime minister's opinion, what should we do now?" Lu Duan heard the queen's words, and his heart suddenly became clearer. Obviously, Empress Li was bewitched by others, so she hesitated like this. Lu Duan immediately said categorically, "The first emperor appointed the crown prince for today, and now that the first emperor has abandoned the world, how can we, as courtiers, do things that go against the last wishes of the first emperor? Besides, the court and the central government cannot be left without a master for a day, and this has a bearing on the future and destiny of the country! We must make a decision on such a major matter, and the queen mother must not have any objections, otherwise there will be endless disasters!" Queen Li didn't have her own opinions, and there was a lot of demagoguery in it, and when she heard Lu Duan say this, she saw that Wang Jien had no shadow, and knew that she couldn't do anything, so she had to let the prince Zhao Dechang ascend the throne.

The crown prince Zhao Dechang ascended the throne and changed his name to Zhao Heng, and he was Emperor Zhenzong. After the ceremony, the ministers came to pay respects, and the first time they went to the palace, it was a curtain. When Lu Duan saw that he was like this, he was puzzled in his heart, he couldn't see Emperor Zhenzong, he just refused to bow down. Empress Dowager Li asked Lu Duan why he didn't worship, and Lu Duan said without hesitation, "Please roll up the curtain and let the emperor sit on the throne, so that we can see clearly and bow again." Empress Dowager Li had no choice but to roll up the curtain and let Emperor Zhenzong sit on the throne. Lu Duan saw clearly that it was indeed Emperor Zhenzong who was sitting on the throne, so he led the ministers to bow down and shouted three times.

The battle for the throne has always been extremely tragic, but fortunately, with Lu Duan, Prince Dechang successfully ascended the throne, and fortunately there was no bloodshed.

Prince Dechang ascended the throne and granted amnesty to the world, but at the same time disposed of Wang Jien and others, demoted them from Beijing, and went out of Beijing with their families. Wang Jien and others failed to make a plan, but were deposed, did not remember the grace of Dechang not to kill, and only thought of revenge in their hearts.