The invasion is acknowledged by recent historians as one of the most important wars of the late medieval period, whereas both sides, especially the Ming, used the most advanced weapons in the world at the time.

After this, the Yongle Emperor appointed Marquises Zhang Fu to prepare and lead the Ming armies for the invasion of Đại Ngu.

[8] In the capital, Thăng Long, turmoil and chaos broke out in 1369–70, provoking a princely coup and a short, bloody civil war.

[9] From the south, Champa under Chế Bồng Nga managed to invade Đại Việt and sacked Vietnamese capital Thăng Long in 1371.

In 1377, Chế Bồng Nga defeated and killed Đại Việt's king, Trần Duệ Tông, in a battle near Vijaya, then marched north and sacked Thăng Long four more times from 1378 to 1383.

[10] Cham invasions, coupled with natural disasters and political intrigues, ultimately induced a radical intellectual and reformer, Lê Quý Ly (c.

[14] Encountering a failed coup by the Trần, Hồ Quý Ly repressed dissenters by executing 370 dissidents, seizing their possessions, enslaving their female relatives, and burying alive or drowning males of all ages.

In May 1403 he sent envoys to the Ming court to request Hồ Hán Thương's investiture on the grounds that the Trần family line had died out and that his son was a royal nephew.

On 4 April 1406, as the party crossed the border into Lạng Sơn, Hồ's partisans ambushed them and killed the Trần prince that the Ming convoy was escorting back.

He ignored the advice of one general to engage invaders in the mountainous terrain on the borders and instead, prepared a riverbank defense in the center of the Red River Delta.

The key to his plan was the Đa Bang fortress (in modern-day Vĩnh Phúc Province) built on the southern bank of the Red River northwest of Đông Đô, at the point where Ming armies from Yunnan and Guangxi would most likely attempt to join forces.

[21] On 11 May (according to Chan) or in the month of July (according to Tsai) 1406, the Yongle Emperor appointed Duke Zhu Neng to lead an invasion with Marquises Zhang Fu and Mu Sheng as second-in-command.

[22] On the eve of departure, the Yongle Emperor gave a banquet at the Longjiang naval arsenal, located at the Qinhuai River in Nanjing.

To withstand Đại Ngu's firearms (huoqi), he ordered the Ministry of Works to manufacture large, thick, and durable shields.

Three months had passed after his departure from Nanjing, when Huang arrived at Longzhou in Guangxi, where he joined the main body of the Ming forces.

Zhu Neng and Zhang Fu would cross the border from Guangxi, while Mu Sheng would invade the Red River Delta from Yunnan.

[21] On November 19, 1406, Ming troops led by Zhang Fu entered Đại Ngu from Guangxi while those under Mu Sheng marched from Yunnan.

Soon afterward, Đại Ngu troops—20,000 at the Ailuu Pass and 30,000 at the Ke-lang Pass—tried to block Zhang Fu's armies with huochong and other weapons, but they were routed easily.

[26] Ming troops attacked the fortress from all directions, employing scaling ladders, xianren dong and gunpowder signal lights (yemingguang huoyao).

"[27] When the Ming troops climbed onto the town wall, the alarmed and bewildered Vietnamese defenders could only shoot a few arrows and fire lances.

Ming generals Luo Wen and Cheng Kuan ordered the firearm regiments to shoot chong and fire lance at the elephants.

As a result the battle lasted for two days, as the town of Đa Bang fell, and the defense line along the Red River collapsed.

"[19] On March 18, 1407, in the Phung Hoa prefecture, Ming troops used da jiangjun chong ("great general cannon") to smash many enemy ships.

[29] On May 4, 1407, a major battle took place at the Hàm Tử Pass (modern-day Khoái Châu District, Hưng Yên Province) on the Red River.

Hồ Quý Ly mustered a reserve force of 70,000 troops and numerous warships and riverboats, which extended to more than ten li.

[33] The Yongle Emperor asked them whether they had killed the former king and had usurped the throne of the Trần royal family, but he received no answer in return.

[28] The Chinese administration conscripted forced labourers and imposed heavy taxes on everything from rice fields to mulberry trees to silk cloth made on local looms.