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.