The Burmese then turned north to depose King Mekuti of Lanna, who had failed to support the Burmese invasion of Ayutthaya in 1563. When Chiang Mai fell to the Burmese, a number of refugees fled to Vientiane and Lan Xang. King Setthathirath, realizing that Vientiane could not be held against a prolonged siege, ordered the city to be evacuated and stripped of supplies. When the Burmese took Vientiane they were forced into the countryside for supplies, where King Setthathirath had organized guerrilla attacks and small raids to harass the Burmese troops. Facing disease, malnutrition and demoralizing guerrilla warfare, King Bayinnaung was forced to retreat in 1565 leaving Lan Xang the only remaining independent Tai kingdom.