In 1664, however, the Dutch used force to exact a treaty granting them extraterritorial rights as well as freer access to trade. At the urging of his foreign minister, the Greek adventurer Constantine Phaulkon, Narai turned to France for assistance. French engineers constructed fortifications for the Thai and built a new palace at Lopburi for Narai. In addition, French missionaries engaged in education and medicine and brought the first printing press into the country. Louis XIV's personal interest was aroused by reports from missionaries suggesting that Narai might be converted to Christianity.
The French presence encouraged by Phaulkon, however, stirred the resentment and suspicions of the Thai nobles and Buddhist clergy. When word spread that Narai was dying, a general, Phetracha, killed the designated heir, a Christian, and had Phaulkon put to death along with a number of missionaries. The arrival of English warships provoked a massacre of more Europeans. Phetracha (reigned 1688-93) seized the throne, expelled the remaining foreigners, and ushered in a 150-year period during which the Thai consciously isolated themselves from contacts with the West.