When he heard that King Narai had become terminally ill, Phetracha killed the rightful heir and beheaded Phaulkon. It was not certain whether he and his son assassinated King Narai or not (official history states that King Narai died in front of him and his son of natural causes). In order to legitimate his coup d'état, Phetracha married the sister and the daughter of the late Narai. His dynasty ruled Ayutthaya for 79 years.
With King Phetracha, according to some modern academics, a representative of the 'nationalist party', who had claimed to defend the kingdom from the French occupation, came to lead the kingdom.[dubious – discuss] He exiled and banned all French representatives. He also negotiated for France to return Bangkok. Only missionaries were allowed to stay.
During his reign, there were many rebellions, as many provinces and vassal states did not accept his rule. Notably, there were wars with Nakhon Si Thammarat and Nakhon Ratchasima's governors.