without conflict. Resurgent Siam At the same time however, Hsinbyushin's decision to sack and destroy Ayutthaya was a long-term strategic failure. While he was immensely successful in acquiring Ayutthaya's wealth and people and in destroying of the Ayutthaya polity, the sacking of Ayutthaya unified and reinvigorated many Siamese elites to pursue a militaristic trajectory that would expand Siam's orbit to its greatest military extent. The resurgent Siam proved to be a formidable competitor to Burma- eventually seizing Lan Na, Vientiane, and Luang Prabang from the Burmese orbit. The initial goal of the Ayutthaya conquest was to end Siamese support of Mon rebels in the Tenasserim coast and Lower Burma. Yet, the new Siamese elites continued to assist Mon rebels and by sending armies to the Tenasserim region for decades, up to the First Anglo-Burmese War, bringing many Mon refugees, both willingly and forcibly, to settle at the new Siamese capital at Bangkok. Furthermore, Burma lost its long-standing vassal Lan Na to the Siamese orbit. Its other recently gained tributaries, Vientiane and Luang Prabang, eventually entered the Siamese orbit only a few years after Hsinbyushin's death. Present-day border The Burmese success in the Sino-Burmese War laid the foundation for the present-day border between China, and Burma. A huge swath of territory from present-day Kachin State to northern and eastern Shan State remains part of Myanmar. The Burmese acquired Tenasserim as a result of the 1765 war, which Siam was unable to regain in later conflicts. Tenasserim had been divided between both Siam and Burma for about 150 years prior to Hsinbyushin's campaigns. The entirety of Tenasserim would remain in Burmese control until 1826, when it was acquired by Britain following the First Anglo-Burmese War before being cede it back 120 years later to an independent Burma. Enmity in relations The enduring enmity felt by Thais towards the Burmese began largely from Hsinbyushin's reign, in the light of the utter and senseless wanton destruction of the Siamese capital Ayutthaya in 1767. A Siamese chronicler wrote: "The king of Hanthawaddy (Bayinnaung) waged war like a monarch but the king of Ava (Hsinbyushin) like a robber." The Burmese invasion of Ayutthaya in 1767 was a conflict between kings, not of ethnicities. A number of Siamese joined the Burmese attack on Ayutthaya in 1767. Warfare of total destruction was normal of the time period, according to Thai historian Sunait Chutintaranond. Later Siamese armies of the