Bayinnaung
Lan Na and Lan Xang (1564–1565)

Although he had finally conquered Siam, he still needed to deal with the middle Tai country. King Mekuti of Lan Na had allied himself with his old rival Setthathirath of Lan Xang. On 23 October 1564, Bayinnaung himself led five massive armies (64,000 men, 3600 horses, 330 elephants) and began a two-pronged invasion of Lan Na. The levies hailed from all over the empire, including Siam whose troops were led by Ramesuan, the former crown prince of Siam. The massive show of force worked. When four southern armies showed up at Lamphun, 20 km south of Chiang Mai, on 25 November 1564, the commanders leading Chiang Mai's defenses simply fled the city. Mekuti now submitted, asking for forgiveness. Bayinnaung spared the broken king's life, and sent him to Pegu. The Burmese king then stayed in Lan Na for the next four months, administering the country. He appointed Queen Visuddhadevi, as the vassal ruler of Lan Na before leaving Chiang Mai on 10 April 1565 to deal with a serious rebellion in Pegu.

Lan Xang proved a much more difficult project however. Three armies led by the crown prince himself invaded Lan Xang, and easily captured Vientiane on 2 January 1565. But King Setthathirath escaped. For the next several months, the Burmese troops fruitlessly chased him and his small band of men around the Laotian countryside. Many troops died of starvation and disease. The Burmese command finally gave up, and the armies left Vientiane on 1 August 1565. They had installed a son-in-law of Setthathirath as vassal king. They also brought back many members of the Lan Xang royalty, including Setthathirath's 18-year-old brother, Maha Ouparat.

Lan Na was to be at peace for the rest of Bayinnaung's reign. At Vientiane, however, the vassal king's authority did not extend much beyond the capital, backed by the Burmese garrison. Setthathirath remained active in the countryside, and would return to Vientiane in late 1567.
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