Mạc Thiên Tứ (, , , December 12, 1699 or December 16, 1705 or January 1, 1718 – June 18, 1780), also known as Mạc Thiên TÃÂch () or Mạc Tông (, ), was a Vietnamese leader who ruled HàTiên from 1735 to 1771 and from 1773 to 1777. He was called Mo Shilin (, ) in Veritable Records of Qing dynasty.
He was the eldest son of Mạc Cá»Âu, and born to a Vietnamese woman from Biên Hòa. He also had a sister, Mạc Kim ÃÂá»Ânh, who was married to the son of the Chinese general Trần Thðợng Xuyên. After his father's death, he received the title of Tá»Âng binh of HàTiên and the noble title Marquess Tông ÃÂức (Vietnamese: Tông ÃÂức hầu) from Nguyá» n lord. His reign saw the golden age of HàTiên. A proper bureaucratic structure was set up, their military saw a massive increase in size and power, castles and business streets were erected, and HàTiên's economy prospered under him. HàTiên became the trade center in Mekong Delta; it became the best-known port in the Gulf of Siam long before the founding of Saigon and Bangkok. In his 1742 letter to Japanese Tokugawa shogunate in Khmer, he called himself Reachea Krong Kampucea Tiptei (, "king of Cambodia") and later Neak Somdec Preah Sotoat (). However, Siamese sources called him both Ong Chien Chun (, "Chinese general") and Phraya Rachasethi (), thus confusing him with Oknya Reachea Sedthei (), the Khmer governor of Banteay Meas.
Mạc Thiên Tứ was also interested in Chinese culture, and built many schools. He adopted a policy of religious tolerance, he treated all religions evenhandedly. Pierre Pigneau de Behaine, a French Catholic priest, was allowed to preach in HàTiên.
According to Vietnamese source, in 1739, a Cambodian army led by "Nặc Bá»Ân" invaded HàTiên, but was utterly defeated by Tứ. From then on, Cambodia did not try to resume HàTiên. Though no Cambodian chronicle recorded this affair, Tứ's victory was highly significant since it allowed HàTiên to enjoy full independence from Cambodia thereafter.
In 1756, the Cambodian king Chey Chettha VII (Nặc Ong Nguyên) died. Thommo Reachea IV (Nặc ÃÂng Yếm) succeeded the throne, but soon was murdered and usurped by Ang Hing (, Nặc Hinh). A Cambodian prince, Ang Ton (Nặc ÃÂng Tôn), fled to HàTiên. In there, Ang Ton became Mạc Thiên Tứ's adopted son. Tứ escorted Ang Ton back to Cambodia, and crowned him the new king as Outey II. In return, Outey ceded Hðáng ÃÂc (modern Sihanoukville), Cần Bá»Ât (Kampot), Trá»±c Sâm (Chhouk), Sài Mạt (Banteay Meas) and Linh Quỳnh (Kiri Vong) to HàTiên.
After War of the second fall of Ayutthaya, Mạc Thiên Tứ hid Siamese prince Chao Chui (, Chiêu Thúy). Chao Chui was a son of Prince Aphai, and also a grandson of king Thai Sa. After Taksin crowned the new king of Siam, Chao Chui was regarded as a big threat by Taksin. Taksin tried to persuade Mạc Thiên Tứ to hand over Chao Chui, but was rejected. Instead, Tứ tried to install Chao Chui as the new Siamese king. In 1769, a HàTiên navy under Trần Hầu (Trần ÃÂại Lá»±c) was sent to attack Chantaburi. Taksin appointed Chiam (Tang Lieng or Trần Liên, Khun Phiphit Wathi), a Teochiu chief of the Chinese junk fleet, as the new vice-governor of Trat with the title Phraya Phiphit. HàTiên navy was defeated by Phraya Phiphit, and had to retreat.
Another incident increased the contradictions between Mạc Thiên Tứ and Taksin. After the defeat of Konbaung Burma, Taksin sent a tributary mission in Canton to require the royal seal, claiming that the throne of Ayutthaya Kingdom had come to an end. However, Tứ reported to Chinese mandarins that Taksin was a usurper. Qianlong rejected Taksin's request, and ordered Taksin to install Prince Chao Chui. Taksin was getting more and more irritated at Tứ's actions.
In 1771, Siamese army led by Taksin and Phraya Phiphit landed at Kampong Som (present-day Sihanoukville) and Kampot, then besieged and captured HàTiên. Tứ had to flee to Gia ÃÂá»Ânh (modern Ho Chi Minh City) and seek refuge for Nguyá» n lord. Taksin appointed Tang Lieng as the governor of HàTiên. Two years later, with the help of Nguyá» n lord, Tứ returned to HàTiên.
In 1775, Nguyá» n Phúc Thuần was defeated by Tây Sán army and fled south. Tứ led troops to support him. Thuần was captured and executed by Tây Sán rebel general Nguyá» n Huá» in 1777. Huá» tried to persuade him to surrender, but was rejected. Tứ fled to Phú Quá»Âc then to Siam. Tôn Thất Xuân, a mandarin of Nguyá» n lord, also fled to Siam for support. In Thonburi, they were warmly welcome by King Taksin. Taksin also asked Tứ to bury their past misunderstandings. Tứ was awarded the Siamese rank and title Phraya Rachasethi Yuan (, lit. "Phraya Rachasethi the Vietnamese"), using the word "Yuan" () to distinguish with the former governor Tang Lieng (Phraya Rachasethi Chin).
Nguyá» n ÃÂnh ascended the lord throne in 1780. ÃÂnh sent envoys to Siam in order to seek alliance with Siam. In the same time, a Siamese merchant ship was looted by ÃÂá» Thanh Nhán, an important military commander of Nguyá» n lord. According to Vietnamese records, taking this opportunity, Nguyá» n Huá» forged a letter from ÃÂnh to Tứ, and sent it to Taksin. In the letter, ÃÂnh planned to raid Thonburi, and ordered Tứ and Tôn Thất Xuân to help him on the inside. Taksin was taken in, and threw Mạc Thiên Tứ into prison. However, Thai record stated that Mạc Thiên Tứ planned to flee back to HàTiên, but was exposed, so Taksin arrested him.
Tứ committed suicide in prison. Two sons, Mạc Tá» Hoàng and Mạc Tá» Dung, his wife, Tôn Thất Xuân and the Vietnamese envoys were executed. His three sons, Mạc Tá» Sanh, Mạc Tá» Tuấn and Mạc Tá» Thiêm, were rescued by Kalahom (Pok) and hid in countryside. After King Rama I ascended the Siamese throne, they were allowed to live in Bangkok. Later, Sinh became new ruler of HàTiên. In 1789, Mạc Công BÃÂnh, a son of Mạc Tá» Hoàng, brought his body back to Vietnam, and buried in HàTiên.
Mạc Thiên Tứ had a large number of offsprings, including: