However, the Burmese King considered that as the Laotian states constituted his base for the maintenance of Burmese power in the territory further east, namely, Luang Prabang and Wienchan (Vientiane), Chiang Mai must be taken back, and so a Burmese army of 6,000 men was sent there to carry out its mission in 1776. The Burmese entered the city, but were forced out by a Thai army under Chao Phya Surasih which had marched to its relief. Chiang Mai had suffered from the recent campaigns so badly that its population was greatly reduced and impoverished, and in the event of a new Burmese attack, it could not defend itself. For these reasons, King Taksin abandoned the city and its remaining inhabitants were transplanted to Lampang. Chiang Mai thus became a deserted city and continued to be in this state for fifteen years. The annexation of Champasak or Bassac led King Taksin indirectly to send an expedition against Wiengchan. In 1777, the ruler of Champasak, which was at that time an independent principality bordering on the Thai eastern frontier, supported the Governor of Nangrong near Khorat, who had rebelled against the Thai King. A Thai army under Chao Phya Chakri was ordered to move against the rebel, who was caught and executed, and having received reinforcements under Chao Phya Surasih, he advanced to Champasak, where the ruler, Chao 0 and his deputy, were captured and were summarily beheaded. Champasak was added to the Kingdom of Siam, and King Taksin was so pleased with Chao Phya Chakri's conduct of the campaign that he promoted him to be Somdech Chao Phya Mahakasatsuek Piluekmahima Tuknakara Ra-adet (meaning the supreme Chao Phya, Great Warrior-King who was so remarkably powerful that every city was afraid of his might)-being the highest title of nobility that a commoner could reach. It would be equivalent to the rank of an English duke. In Vientiane, a Minister of State, Pra Woh, had rebelled against the ruling Prince and fled to the Champasak territory, where he set himself up at Donmotdang near the present city of Ubon. He made formal submission to Siam, when she annexed Champasak, but after the withdrawal of the Thai army, he was attacked and killed by the Vientiane troops. This action was instantly regarded by King Taksin as a great insult to him, and at his command, Somdech Chao Phya Mahakasatsuek invaded Vientiane with an army of 20,000 men in 1778. It would be useful here to briefly summarise the history of Laos which had been separated into two principalities of Luang Prabang and Vientiane since the beginning of the eighteenth century. The Prince of Luang Prabang, who was in enmity with the Prince of Vientiane, submitted to Siam for his own safety, bringing his men to join Somdech Chao Phya Mahakasatsuek in besieging the city. After a siege of about four months, the Thais took Vientiane and carried off the image of the Emerald Buddha to Thon Buri.