driven back near Kanchanaburi with heavy losses. Meanwhile, a much larger Siamese army invaded Lan Na, catching the Burmese command completely off guard. The Siamese captured Chiang Mai on 10 February 1663, and drove back Burmese forces that arrived belatedly. In November 1663, Siam launched a two-pronged invasion of the Tenasserim coast: Martaban and Moulmein in the north and Tavoy in the south. Burmese defences withstood several Siamese onslaughts until May 1664 when the invaders retreated before the rainy season arrived. Meanwhile, the Siamese garrison at Chiang Mai was holed up in a deserted city, and its troops were constantly ambushed by resistance forces whenever they ventured out of the city. In late November 1664, the Siamese evacuated Chiang Mai, and returned. This was the last major war between the two kingdoms until 1760 although they traded small raids in 1675–1676, and in 1700–1701. Fall of the Toungoo dynasty Lan Na (1727–1732) In October 1727, the Burmese governor of Lan Na was assassinated because of high taxation. An army was rushed to Chiang Mai via Mone. The army retook the city after a fierce battle. But the army was ambushed by the rebels as the troops left the city in early 1728. Another expedition in 1731–1732 could not overcome the defences at Chiang Mai. Southern Lan Na (Ping valley) was now independent of Ava. Manipuri raids (1724–1749) Manipur was a tributary to Burma in the 16th century (1560–1596) but had gone its own way since. It raided Upper Chindwin region in 1647 and 1692. However, in 1704, the raja of Manipur presented his daughter to Ava. Starting in the 1720s, Manipur under the leadership of Pamheiba (Gharib Nawaz) became a thorn to Upper Burma. In early 1724, the Manipuris raided Upper Burma. In response, an expedition force of 3,000 men marched to Manipur in November 1724. The army was ambushed in the swamps at Heirok, and retreated in haste. The Manipuris then returned ten years later. From 1735 to 1741, Manipuris raided the Upper Chindwin regions, increasingly deeper with each raid. Burmese defences were simply bypassed the Manipuris on their horseback. In December 1739, they reached as far as Sagaing, and looted and burned everything insight. The Burmese defences finally stopped them at Myedu in early 1741, with each side agreeing to an uneasy truce. But the Manipuris had annexed the Kabaw valley. The truce did not last. Another raid