Vietnamese-Laotian War (1479–80)

The history of Lan Xang began in 1351 when Fa Ngum, the exiled prince of the Tai kingdom of Muang Sua, led an army north from the Khmer Empire to reclaim the throne of his forefathers. As Fa Ngum traveled toward Muang Sua, his army grew into a powerful force by defeating rivals, subduing local mandalas, and gaining the support of the Kingdom of Muang Phuan.[3][4]

Đại Việt at the time was an independent kingdom enjoying 400 years of freedom from Chinese domination. The Vietnamese, however, were in the midst of a centuries long conflict with the powerful Champa Kingdom. Concerned about potential attacks from the Cham, the king of Đại Việt sought Fa Ngum out in 1351 and entered into a border treaty to preclude war with the warrior prince.[5][6][4]

Two years later Fa Ngum successfully conquered Muang Sua and secured the crown for himself. One of the first actions that the newly crowned king took at the time was to rename the country Lan Xang. After the borders were secured in the early years after Fa Ngum’s conquests, Lan Xang lived peaceably with its neighbors for over half a century. Đại Việt’ and the Champa Kingdom, however, continued their war.[7][8]

In 1402, Lan Xang entered into a treaty with the Ming Dynasty of China and was recognized as a “tributary ‘barbarian’ ruler responsible for maintaining peace and security on China’s southern frontier.” Shortly thereafter the Ming invaded Đại Việt’. In 1407 the Chinese defeated the Vietnamese and began their fourth period of domination.[9][10]

During the twenty-year span of Đại Việt’s fourth period of Chinese domination, the good relationship between Lan Xang and Đại Việt’ began to degenerate. In 1418, Lê Lợi, the son of a Vietnamese aristocrat, initiated a guerrilla war against the Ming. In 1421 during Đại Việt’s fight for independence, the king of Lan Xang offered Lê Lợi military assistance. When the Lao forces arrived in Đại Việt’, however, they immediately took the side of the Chinese. Although the participation of Lan Xang’s forces in the war eventually proved to be short-lived, their action was seen by the Vietnamese as betrayal.[10][11][12]

In 1428, Lê Lợi eventually defeated the Ming and established a new Vietnamese dynasty. For the next 32 years, Đại Việt’ and Lan Xang lived peaceably. During this time, Lan Xang was preoccupied by internal strife while Đại Việt’ warred again with the Cham.[13][14][15]

Beginning with the reign of Vietnamese king Lê Thánh Tông in 1460, Đại Việt’ began to act aggressively toward its neighbors. Neighboring Laotian territories were annexed and designated as tributary to Đại Việt’. Skirmishes were likely fought, but an all-out war did not develop as the Vietnamese continued to be concerned about threats from their historical enemies, the Chinese and the Cham. In 1471, Đại Việt’ was strong enough and confident enough that they invaded the Champa Kingdom, overwhelmed their army, and effectively ended the Cham polity.[16]

In that same year, Đại Việt’ also moved to make Lan Xang’s tributary mandala, Muang Phuan, an administrative prefecture with Vietnamese mandarins as administrators. This overt action created a revolt which ultimately resulted in a massacre of Vietnamese occupation forces in 1478. As a result, the Vietnamese invaded Lan Xang in 1479 and the war between the two kingdoms commenced.[17]

With respect to the invasion and war, the Vietnamese felt that they were justified threefold. Most importantly, the Vietnamese king Lê Thánh Tông believed that Lan Xang was responsible for the massacre of Vietnamese troops in 1478. Secondly, the Vietnamese wanted revenge for the betrayal that they suffered in 1421 during their war of independence against the Chinese when military help was promised by Lan Xang but not delivered. And finally as a third justification, the Vietnamese king was highly insulted during these times when he was sent a chest containing the dung of a white elephant by the Laotian king. Because of this final affront, the conflict came to be known as “the White Elephant War.”[18][17]

At the outset of the war, the Vietnamese king ordered a large army to cross into Muang Phuan and from there to attack Lan Xang. Estimates of the tactics used by the Vietnamese vary from a single wave of three columns to a single wave of five columns to multiple waves of an amassed force. As the Vietnamese advanced, the Lao army formed and marched to confront the invaders. The two armies first met on the Plain of Jars in Muang Phuan where a battle was fought for several days. Estimates of the number of men in the armies were as large as 200,000 men on a side. Historians believe, however, that such estimates were “grossly exaggerated.”[19][17][20]

The initial battle in Muang Phuan was won by the Vietnamese and the Lao army retreated. The Vietnamese army continued to advance and ultimately sacked Lan Xang’s capital, Xieng Dong Xieng Thong (Luang Prabang). Losses were reported to be very high. Food supplies were seized by the Vietnamese; houses and villages were burned and destroyed. Populations of Lao citizens fled as did the elderly Lao king, Chakkaphat Phaen Phaeo.[21]

After losing their capital, the Laotians rallied. There are, however, multiple versions of this part of the war. One account reported that Then Kham, a son of the Laotian king, who was serving as the governor of Muong Dan Sai, attacked the Vietnamese with fresh units of the Lao army. In this history, the exhausted and depleted Vietnamese were defeated at the Battle of Pāk Phūn and then straggled back to Đại Việt’.[19]>[21]

A second account of the fighting reported that the Vietnamese split their forces after the capture of the Lao capital intent upon continuing the offensive and conquering the mandala Lan Na by means of a pincer attack. In this chronicle, the Vietnamese troops in the south were defeated by fresh troops from Lan Xang along with an army from Nān, a vassal state of Lan Na; meanwhile the Vietnamese troops in the north withdrew voluntarily after negotiations and/or under the threat of an invasion from the Chinese.[1]

Regardless of the actual scenario, the Vietnamese withdrew back to their border and the war ended with the exception of one last attack the following year against Muang Phuan intended “as punishment for aiding Lan Xang.”[22]

After the war, the northern part of kingdom Muang Phuan (today Houaphanh and Xiangkhouang) was renamed "Tran Ninh" by Vietnamese and merged with Nghe An province of Dai Viet, the southern remain under Lan Xang control. Lan Xang and the Dai Viet lived alongside one another in a peaceful manner for the next two centuries until Lan Xang’s decline and partition in the early 18th century.[19] In Lan Xang, Buddhist monks from the major monasteries organized the rebuilding of the Laotian capital. Ultimately, the destruction and rebirth of Xieng Dong Xieng Thong was a catalyst for a golden age in Lan Xang where governance was fine-tuned, art flourished and beautiful temples were erected.[23] During this time, Lan Xang enjoyed close relations with the Ayutthaya and Lan Na Kingdoms and emerged as one of the most powerful states in Southeast Asia.[24]

At the end of the war with Lan Xang, Đại Việt’ retained its position as the single strongest kingdom in Southeast Asia. Over the next two centuries no longer impeded by the Cham, Đại Việt’ used its strength to expand to the south first colonizing what is now central Vietnam and by the 18th century occupying Prey Nokor and encroaching into the Mekong Delta.[25][26] For the most part, however, Đại Việt’ was occupied during these times by continuing internal conflict including peasant revolts against the Later Lê dynasty; the revolution and rule of the Mạc dynasty; and the fight for power between the Trịnh lords and the Nguyễn lords.[27].[28]