Philippe-Thomas Chabert de Joncaire

Joncaire joined the colonial French army in 1726 and attained the rank of second ensign in 1727.[1] On July 23, 1731, he married Madeleine Renaud Dubuisson.[1]

In 1735, Joncaire succeeded his father as the principal interpreter and political agent from New France to the Iroquois.[1] His responsibilities included easing tensions between the indigenous peoples and the French when either side acted aggressively.[1] He also negotiated a deal for the Senecas to supply Fort Niagara with fresh meat.[1] By 1744, his successes resulted in the offering of a dead-or-alive reward by the British.[1]

Map of the route followed by Pierre Joseph Céloron de Blainville along the Ohio River in 1749, drawn by Joseph Pierre de Bonnecamps. "Sinhioto" appears at the lower edge.

Joncaire resigned his post on the frontier in 1748 with a claim of ill health, two years after the death of his wife.[1] The following year, he was recalled to be the interpreter for Pierre-Joseph Céloron de Blainville's expedition along the Ohio River.[1] He was captured in Sonioto by Shawnees while establishing first contact and was nearly killed before the intervention of an Iroquois chief.[1][5]

Chiningué (Logstown) and other Native American villages, most circa 1750s

In early July 1750, Joncaire was sent with 12 soldiers to Chiningué to establish a permanent French base.[1] He found that the native population preferred the traders from Pennsylvania and Virginia over the French.[1] By 1751, Joncaire held the rank of captain in the French colonial army.[1] When larger French forces arrived with Paul Marin de la Malgue in 1753, he found support among the local Delaware and Shawnee who wanted to challenge the Iroquois.[1]

In 1753, Governor Jean de Lauson sought to build a fortified trading post at the confluence of the Allegheny River and French Creek at Venango.[6] That year, the English traders were expelled from Venango and Joncaire established Fort d'Anjou with a permanent garrison at the location.[6]

In December 1753, Major George Washington arrived at Fort d'Anjou on an expedition to deliver British demands and assess the French military situation.[7] Joncaire directed Washington to his superior officer at Fort LeBoeuf but informed Washington during a dinner about French intentions to "take possession of the Ohio".[7]

In 1754, Philippe-Thomas was replaced by Michel Maray de La Chauvignerie as the officer in charge of constructing the fort, which was eventually renamed Fort Machault.[6]