Zhu Yuanzhang's Nanjing Dream and Zhu Di's Dilemma: Why an Emperor Who Appeared Only After 500 Years Struggles to Escape the Mongol Shadow

When discussing the most militarily talented rulers of the Ming Dynasty, besides the founding emperor Zhu Yuanzhang, his fourth son Zhu Di must also be mentioned. Interestingly, the order established by Zhu Yuanzhang himself became Zhu Di’s greatest constraint. Zhu Yuanzhang chose Nanjing as the capital; this decision seemed prudent but actually laid the groundwork for Zhu Di’s later northern expeditions. When Zhu Di finally decided to move the capital to Beijing, he was attempting to break the political legacy left by Zhu Yuanzhang—and this choice ultimately changed the future of the Ming Dynasty.

An Emperor’s Power Dilemma: How to Break Through Zhu Yuanzhang’s Political Legacy

Zhu Di did not inherit the throne through legitimate succession but seized power through the bloody military coup known as the Jingnan Campaign. His grandson, Emperor Jianwen Zhu Yunwen, was the rightful heir, but Zhu Di overthrew this arrangement by force. This meant Zhu Di’s legitimacy was inherently questionable—he needed to prove his rule’s legitimacy through other means.

The political center Zhu Yuanzhang established in Nanjing embodied his core ideology: using the Yangtze River basin as the heart of the empire, defending against remnants of the Mongols to the north. Under this layout, Nanjing was not only the political hub but also a symbol of Zhu Yuanzhang’s legitimacy. If Zhu Di recklessly moved the capital, it would directly challenge Zhu Yuanzhang’s decisions—causing a major upheaval within the bureaucratic system and public opinion at the time.

Zhu Di’s cleverness lay in drawing inspiration from the historical example of Emperor Xiaowen of Northern Wei, who moved the capital. Xiaowen aimed to relocate from Datong to Luoyang to promote Han Chinese cultural reforms but faced fierce opposition from conservative officials. Under pressure, he used the pretext of a “southern expedition,” assembling tens of thousands of troops to march south. During the journey, heavy rains dampened morale, and upon reaching Luoyang, many officials petitioned to halt the campaign and instead requested the city be made the new capital—Xiaowen acquiesced. This “excuse” successfully bypassed political resistance.

Zhu Di learned this lesson: before relocating the capital, he needed to build enough political capital under the guise of military action. Therefore, he prioritized the northern expedition against the Mongols, using a series of victories to pave the way for the move to Beijing. This was not just military expansion but a carefully crafted political strategy.

The Truth Behind Five Northern Expeditions: Defeating the Mongols but Failing to Conquer History

Zhu Di’s first northern expedition began with a seemingly simple incident—an envoy he sent north was killed by forces of the Northern Yuan. Enraged, Zhu Di promoted Qi Fu to commander and led a million-strong army north to fight the Tatars. At that time, the Mongolian steppe was already divided: the Tatars were the legitimate Northern Yuan, ruled by Genghis Khan’s descendants, controlling the eastern steppes; the Wala tribe was a rising Mongol faction that had become powerful over decades, controlling the western steppes, with both vying for the legitimacy of the Northern Yuan.

At that time, the Tatars were under the command of the Grand Marshal Arughtai, who supported Genghis Khan’s descendant Bunyashiri as Great Khan. However, this faction was secretly supported by the Ming to counterbalance the Wala. As a result, Qi Fu underestimated the enemy and was ambushed, leading to the complete destruction of the million-strong army. News of this defeat enraged Zhu Di, who decided to lead the army himself.

In 1410, Zhu Di assembled 500,000 elite troops and marched north. This was more than just a military campaign—it was a national-level mobilization of resources, preparing for the later move of the capital. Facing the Ming’s formidable force, Arughtai was helpless; the Tatars were defeated, and Bunyashiri, along with only seven followers, fled westward to the Wala tribe, where he was eventually killed by their leader, Mahamu. Zhu Di’s forces pursued to Ulaan River—Genghis Khan’s birthplace, at the border of today’s Russia and Mongolia. This achievement was celebrated as “only an emperor like Zhu Di could reach here in five hundred years.”

However, Arughtai was not a simple figure. After surrendering to the Ming, he skillfully assessed the situation and, taking advantage of Zhu Di’s support, turned against the Wala leader Mahamu, eliminating him and reestablishing Tatars as the dominant force on the steppes. Zhu Di saw that the Wala might unify the Mongol tribes and threaten Ming borders, so he supported the defeated Arughtai to reorganize the Tatars, leading to renewed confrontation between the two major steppe powers.

Yet, the expansion of the Wala tribe did not stop. In 1414, Zhu Di launched a second northern campaign with another 500,000 troops. During this campaign, Ming forces fought the Wala at the Kurlen River. Both sides suffered heavy losses, but the Ming had a clear military advantage—only 30,000 Wala elite troops against 500,000 Ming soldiers. The Wala were defeated, and Arughtai expanded westward, destroying the Wala leadership entirely. This time, Zhu Di seemingly resolved the northern threat, and the northern border was relatively stable.

But Zhu Di’s problem was that he only knew how to fight—he lacked governance skills. In all five expeditions, although he repeatedly destroyed Mongol forces, he never established an effective administrative system on the steppes—no garrisons, no administrative institutions—relying solely on military suppression. Once Ming troops withdrew, the Tatars and Wala tribes quickly regrouped.

The third, fourth, and fifth expeditions became increasingly futile. In 1422, Zhu Di launched another campaign, but Arughtai had already heard the news and fled; the Ming army returned empty-handed, only defeating the Ulianghai tribes allied with Arughtai on the way back. In 1423, Zhu Di launched yet another expedition; the Wala tribe struck first, destroying the Tatars, but Zhu Di’s forces failed to capture the main enemies. In 1424, the fifth and final campaign was even more tragic—due to rapid marching and logistical failures, supplies ran out, and the army had to retreat. More tragically, Zhu Di died en route back. This failed military campaign marked the end of a legendary ruler’s life on the Mongolian steppe.

Why Did He Fall Into the “Son of Heaven Guarding the Pass” Dilemma?

On the surface, Zhu Di defeated the Mongols, but in reality, he left two major hidden dangers. First, he never truly occupied or governed the territories he conquered. His five expeditions only cleared the battlefield—once the troops withdrew, the Mongol tribes, especially the Tatars and Wala, quickly reassembled. Zhu Di achieved tactical victories through force but lost the strategic advantage.

Second, Zhu Di’s successors failed to maintain his military pressure. After his death, Ming rulers could no longer mobilize hundreds of thousands of troops for northern campaigns. As a result, Mongol forces gradually recovered and began frequent raids into Ming territory.

More critically, the Jingzhao Incident (the Tumu Crisis) occurred. During Zhu Yuanzhang’s era, northern Shanxi and Hebei still remained under Ming control, forming a buffer zone between the capital and the steppes. But during Emperor Yingzong’s reign, the Tumu Crisis led to the complete destruction of Ming’s elite forces, losing large parts of northern territory. From then on, Beijing was directly exposed to Mongol threats—the capital became a frontline.

This is the origin of the phrase “The Son of Heaven guards the gates of the country.” On the surface, it sounds heroic: the emperor personally defends the frontier. But in reality, it was the inevitable result of the accumulated policy failures of Zhu Yuanzhang and Zhu Di. When Zhu Yuanzhang chose Nanjing as the capital, he built a protective buffer—enough space to buffer northern threats. But Zhu Di, seeking political legitimacy, disregarded Zhu Yuanzhang’s wishes and moved the capital to Beijing, exposing the emperor directly to danger. His northern expeditions, while victorious in battle, did not bring lasting peace.

The Ironic Legacy: How Zhu Yuanzhang’s Heritage Became Zhu Di’s Dilemma

Zhu Yuanzhang’s “Imperial Instructions” explicitly stipulated that the capital should be in Nanjing—this was not just a geographical choice but a deep strategic consideration for stability. Nanjing, backed by the Yangtze River, was easy to defend and far from the plains of the steppe, serving as a relatively safe base. Under this framework, Zhu Yuanzhang could focus on internal governance without excessive concern for the Mongol remnants to the north.

But Zhu Di changed everything. Moving the capital to Beijing seemed to strengthen control over the north, but actually weakened the empire’s defensive depth. To justify the relocation, he had to continually demonstrate his ability to manage the north, leading to a series of northern campaigns. These campaigns achieved short-term success but failed to address the core issue—Zhu Di never fundamentally eliminated the Mongol threat, only suppressed it temporarily.

By the late Ming, as Zhu Di’s military deterrent waned, Mongol forces revived, and the buffer zone established in Zhu Yuanzhang’s time was lost. The tragic result was inevitable: the emperor had to “guard the gates,” and the capital became a frontline of warfare.

This dilemma was not simply due to Zhu Di’s incompetence but was rooted in his alteration of Zhu Yuanzhang’s strategic system. Zhu Yuanzhang designed a sustainable defense framework, while Zhu Di relied on continuous military suppression. When this suppression weakened, the entire system began to collapse.

Ironically, even at his strongest, Zhu Di only temporarily suppressed the problem, not solved it. His victory with 500,000 troops exchanged for a capital that had to remain perpetually vigilant. From this perspective, the phrase “The Son of Heaven guards the gates of the country,” which sounds heroic, is actually a tragic reflection—highlighting not the empire’s strength, but the cost of the policies of Zhu Yuanzhang and Zhu Di.