When the Hongwu Emperor (Ming Taizu) was in power, he learned from historical lessons about eunuchs monopolizing power and causing state chaos. He established a rule forbidding eunuchs from interfering in state affairs. He inscribed this rule on a large iron plaque and hung it in the palace, hoping his descendants would abide by it generation after generation. However, during the reign of the Yongle Emperor (Ming Chengzu), this rule was abolished.
The Yongle Emperor seized the throne from his nephew and, fearing opposition from ministers, placed special trust in eunuchs close to him. After relocating the capital to Beijing, he established the "Eastern Depot" outside Dong'an Gate specifically to spy on officials and commoners for any suspicion of rebellion. Fearing that external ministers might be unreliable, he appointed trusted eunuchs as directors of the Eastern Depot. Thus, the power of eunuchs gradually grew. By the time of the Xuande Emperor (Ming Xuanzong), even the task of reviewing memorials was delegated to a eunuch scribe known as the Director of Ceremonial. This further increased eunuch power.
One year, the imperial palace recruited a group of eunuchs. A ruffian from Weizhou (present-day Yu County, Hebei; pronounced "Yù"), named Wang Zhen, had studied a little when young but failed several imperial examinations. He became a local schoolmaster, but later committed a crime that should have led to conscription into the army. Hearing that the palace was recruiting eunuchs, he voluntarily entered the palace to become one. Literate eunuchs were few in the palace, but Wang Zhen had a basic command of writing, so everyone called him "Master Wang." Later, the Xuande Emperor assigned him to teach the crown prince Zhu Qizhen. The young Zhu Qizhen loved to play, and Wang Zhen devised all kinds of ways to make him enjoy himself thoroughly. Zhu Qizhen became very fond of him.
After the Xuande Emperor's death, the nine-year-old crown prince Zhu Qizhen ascended the throne, becoming the Zhengtong Emperor (Ming Yingzong). Wang Zhen became Director of Ceremonial, helping the emperor review memorials. The Zhengtong Emperor pursued pleasure exclusively and never attended to state affairs. Seizing the opportunity, Wang Zhen took control of military and political power. Any high-ranking official who dared to offend Wang Zhen would either be dismissed or sent into exile. Some princes and aristocrats flattered Wang Zhen, calling him "father-in-law." Wang Zhen's power reached its peak.
At this time, the Oirat (pronounced "là") tribe of the Mongols in northern China grew powerful. In 1449 AD, the Oirat leader Esen sent 3,000 envoys to Beijing to present horses as tribute and request rewards. Wang Zhen discovered Esen had falsely inflated the number of envoys and reduced the reward amount and horse prices. Esen's request for a marriage alliance between his son and the Ming dynasty was also rejected by Wang Zhen. This enraged Esen, who then led Oirat cavalry to attack Datong. The Ming generals defending Datong fought back but were decisively defeated by the Oirat forces.
Border officials urgently reported the crisis to the court. The Zhengtong Emperor hastily convened ministers to discuss countermeasures. Datong was not far from Wang Zhen's hometown of Weizhou, where he owned vast estates. Fearing his lands would be occupied by the Oirat army, Wang Zhen strongly advocated that the emperor lead troops personally on an expedition. Kuang Ye (pronounced "kuàng yě"; "Ye" meaning "wild"), the Minister of War (the Minister and Vice-Minister of War were the chief and deputy heads of the military department), and Vice-Minister Yu Qian believed the court was unprepared and opposed a personal expedition. The Zhengtong Emperor, lacking independent judgment, followed Wang Zhen's advice regardless of ministerial warnings and rashly decided on a personal campaign.
The emperor ordered his younger brother, Prince Cheng (pronounced "chéng") Zhu Qiyu (pronounced "yù"), and Yu Qian to remain in Beijing to guard the capital, while he, along with Wang Zhen, Kuang Ye, and over a hundred other officials, led an army of 500,000 men out of Beijing, marching grandly towards Datong.
This expedition was poorly prepared from the start, and the army's discipline was lax. Along the way, they encountered violent storms. After only a few days, food supplies ran short, leaving soldiers hungry and cold. Even before encountering Oirat troops, they were already complaining bitterly. When they neared Datong, soldiers saw the fields outside the city littered with corpses of Ming soldiers, making them even more fearful. One minister, noticing the low morale, advised the emperor to retreat, but was severely scolded by Wang Zhen and forced to kneel in punishment for a day.
A few days later, the Ming vanguard was annihilated by Oirat forces near Datong, and various Ming units began retreating in disorder. Only at this point did Wang Zhen realize the danger and order a retreat back to Beijing. Retreat should have been as swift as possible, but Wang Zhen wanted to show off in his hometown of Weizhou and persuaded the emperor to stay there for a few days. Hundreds of thousands of troops left Datong, running forty li towards Weizhou. Then Wang Zhen reconsidered: such a massive army arriving in Weizhou would surely damage the crops in his family's fields. In a hurry, he issued another order to turn back. This折腾 (troublesome delay) prolonged the retreat, allowing the pursuing Oirat forces to catch up.
The Ming army retreated while fighting, finally reaching Tumu Fortress (east of present-day Huailai, Hebei). By then, the sun had just set. Someone advised the emperor to press on while it was still light, reach Huailai City (present-day Huailai, Hebei), rest there, and make a strong defense against the approaching Oirat army. But Wang Zhen insisted the army stop at Tumu Fortress because several thousand carts transporting his personal property had not yet arrived. Although called a "fortress," Tumu had no real fortifications to defend. The Ming army, having marched for days, was desperately thirsty, but Tumu had no water source. A river fifteen li away was already occupied by Oirat forces. Soldiers dug wells on the spot, reaching two zhang deep, but found no water.
The next morning, just as dawn broke, Oirat troops arrived at Tumu Fortress, tightly surrounding the Ming army. Knowing breakout was impossible, the Zhengtong Emperor sent someone to sue Esen for peace. Esen learned the Ming emperor still commanded a substantial force; a direct battle would cause heavy losses to his own side. So he pretended to agree to negotiations and halted his attack.
The emperor and Wang Zhen believed this to be true and were overjoyed. They ordered soldiers to go find water nearby. Soldiers rushed out of the trenches toward the riverbank in a panic, creating chaos. Officers could not control them even if they tried.
At that moment, the long-ambushing Oirat soldiers charged from all directions, each wielding a long saber and shouting loudly: "Surrender and you shall not be killed!"
Upon hearing this, Ming soldiers immediately discarded their armor and helmets, fleeing wildly. The Oirat army pursued relentlessly. The number killed by weapons or trampled to death in the chaos was countless. Kuang Ye was also killed amid the confusion.
The emperor and Wang Zhen, accompanied by a group of imperial guards, attempted to break through several times but failed. Wang Zhen, who usually lorded over others, now trembled with fear. Imperial guard commander Fan Zhong, who had long hated this traitor who brought disaster to the nation, angrily declared: "I will kill this villain for the sake of the people under heaven!" Saying this, he raised his large iron hammer and smashed it onto Wang Zhen's head, ending his life. Fan Zhong then charged into the Oirat ranks, fought fiercely for a while, and fell mortally wounded by gunfire.
Seeing escape was hopeless, the Zhengtong Emperor dismounted, sat cross-legged on the ground, and waited to die. Oirat soldiers rushed forward and captured him. Historically, this event is known as the "Tumu Crisis."
After this battle, over half of the 500,000-strong Ming army was lost, severely weakening the Ming dynasty. The Oirat leader Esen became even more arrogant, and Beijing came under threat from Oirat forces. The responsibility of defending the capital now fell upon the emperor's younger brother, Prince Cheng Zhu Qiyu, and Yu Qian.