In 1448 during the disorder of the Maha Devi, Muang Phuan and some areas along the Black River were annexed by the kingdom of Đại Việt and several skirmishes took place against Lanna Kingdom along the Nan River.^[25] In 1471 Emperor Lê Thánh Tông of Đại Việt invaded and destroyed the kingdom of Champa. Also in 1471, Muang Phuan revolted and several Vietnamese were killed. By 1478 preparations were being made for a full-scale invasion of Lan Xang in retribution for the rebellion in Muang Phuan and, more importantly, for supporting the Ming Empire in 1421.^[26]

Around the same time, a white elephant had been captured and brought to King Chakkaphat. The elephant was recognized as a symbol of kingship throughout Southeast Asia and Lê Thánh Tông requested the animal's hair to be brought as a gift to the Vietnamese court. The request was seen as an affront, and according to legend, a box filled with dung was sent instead. The pretext having been set, a massive Viet force of 180,000 men marched in five columns to subdue Muang Phuan, and was met with a Lan Xang force of 200,000 infantry and 2,000 elephant cavalry in support which was led by the crown prince and three supporting generals.^[27]

The Vietnamese forces won a hard-fought victory and continued north to threaten Muang Sua. King Chakkaphat and the court fled south toward Vientiane along the Mekong. The Vietnamese took the capital of Luang Prabang, and then divided their forces to create a pincer attack. One branch continued west, taking Sipsong Panna and threatening Lanna, and another force headed south along the Mekong toward Vientiane. A contingent of Vietnamese troops managed to reach the upper Irrawaddy River (modern-day Myanmar).^[27] King Tilok and Lanna preemptively destroyed the northern army, and the forces around Vientiane rallied under King Chakkaphat's younger son Prince Thaen Kham. The combined forces destroyed the Vietnamese forces, which fled in the direction of Muang Phuan. Although numbering only about 4,000 men, the Vietnamese destroyed the Muang Phuan capital in one last act of vengeance before retreating.^[28]

Prince Thaen Kham then offered to restore his father Chakkphat to the throne, but he refused and abdicated in favor of his son who was crowned as Suvanna Balang (The Golden Chair) in 1479. The Vietnamese would not invade the unified Lan Xang for the next 200 years, and Lanna became a close ally to Lan Xang.^[29]