Sen Soulintha

As one of Setthathirath’s most trusted generals Sen Soulintha encouraged the professionalization of Lan Xang’s army, and promoted the use of small mobile units.[19] In 1558, Burmese forces led by Thado Minsaw, took the whole of the Kingdom of Lan Na including those cities won by Setthathirath.[20] By 1560 Setthathirath had formally transferred the capital of Lan Xang from Luang Prabang to Vientiane, for a number of reasons not the least of which was the importance of Vientiane as the most populous and economically vital city in Lan Xang, and the increasing threat of Burmese presence throughout the region.[21] Sen Soulintha played a major role in the building campaign Setthathirath sponsored in Vientiane and throughout Lan Xang.[17] Sen Soulintha also played a major role in resisting two subsequent Burmese during the reign of Setthathirath, and two attempted sieges of Phitsanulok.[22]

In 1571 Setthathirath died while on a military campaign in southern Lan Xang near Attapeu.[23] The exact circumstances of Setthathirath’s death are unknown, he may have been wounded or killed while fighting the Khmer under Barom Reachea I, or had been murdered in a plot sponsored by Chao Chantha Siharath the Governor of Nakhon.[7][24] Sen Soulintha led the armies back to Vientiane, where Setthathirat’s only heir Prince No Muong was still a minor.[7] A succession dispute erupted between Sen Soulintha, who was Prince No Muong’s maternal grandfather, and Chao Chantha Siharath for the regency.

The chronicles implicate that the Sena, or royal council, which was headed by the highest prelates in Lan Xang, was able to maintain peace between the factions for only a few months.[17] Sen Soulintha then raised an army of his supporters and killed Chao Chantha Siharath.[17][25] Once established as regent, Sen Soulintha found himself facing powerful opposition based on his common birth, his favorite status with Photisarath and Settathirath, and the role he played in killing Chao Chantha Siharath. He became known derisively as Chao Pu Lan or “royal grandfather,” a reminder that Prince No Muong was the son and true heir of Setthathirath.[26] In an attempt to overcome the factions at court, he deposed his own grandson Prince No Muong in 1572 and took the regnal name Samdach Brhat-Anya Chao Sumangala Ayaka Budhisana Raja Sri Sadhana Kanayudha. Following his coronation a number of vassals refused to accept Sen Soulintha, which led to reprisals and an exodus from Vientiane to the south in Champasak and Roi Et.[26][27]

The discontent and bitter succession dispute reached Bayinnaung, who seized the opportunity to demand Sen Soulintha abdication and the surrender Lan Xang around 1573.[28][26] Sen Soulintha had the Burmese ambassadors killed.[26] An army set out to punish Sen Soulintha under the Burmese Chief Minister Binnya Dala.[8] Despite his unpopularity as king, Sen Soulintha remained a competent general, and drove back the army. Bayinnaung was enraged at the failure and permanently exiled Binnya Dala as a result.[9] In 1574 Bayinnaung himself led a massive invasion force to at last bring Lan Xang firmly within the Taungoo Empire. Sen Soulintha ordered the preemptive evacuation of Vientiane, and attempted to conduct a third guerrilla campaign against the Burmese but his popular support was too weak.[27] Vientiane was quickly taken and Sen Soulintha and his son Nakhon Noi were captured. In place of Sen Soulintha, Bayinnaung installed the former Ouphahat, and Setthathirath’s brother, Prince Tha Heua on the throne with the regnal name Voravongsa I.[11][12]

Toungoo Empire at its greatest extent (c.1580)

Lan Xang had previously been invaded by the Đại Việt in 1478,[29] and the Burmese had briefly held the capital in 1564 and 1570, but with the third Burmese invasion in 1575 Lan Xang would have to formally recognize Burmese suzerainty for a period of over twenty years. However, faced with internal rebellion and perennial conflict with Ayutthaya the Taungoo Empire struggled to maintain control of Lan Xang throughout the period.

In 1579 Voravongsa I and his family were killed while fleeing from a popular rebellion which threatened the capital.[4] On 17 October 1579, Bayinnaung dispatched a sizable army (22,000 men, 1200 horses, 120 elephants) to restore order.[14] According to Lao histories, it was during this campaign that Sen Soulintha was installed as a vassal king, factoring that the lack of popular support would ensure that Sen Soulintha remained loyal to Pegu.[15][30] In 1581 Bayinnaung died, and his son Nanda Bayin succeeded him as Emperor of a vast territory which was quickly disintegrating into local factions and regional disputes.[30] In 1582 Sen Soulintha died at about the age of 70, leaving his son Nakhon Noi to reign briefly before he was deposed and killed, setting off another round of succession disputes and a period of interregnum until the accession of Setthathirath’s son and heir Keo Koumane around 1591.[31]