Early career Joncaire joined the colonial French army in 1726 and attained the rank of
second ensign in 1727.
Chiningué In early July 1750, Joncaire was sent with 12 soldiers to
Chiningué to establish a permanent French base. He found that the native population preferred the traders from
Pennsylvania and
Virginia over the French. In August 1753, the French decided to occupy the trading post and gunsmith shop owned by
John Fraser, which Fraser had operated since 1740, and from which Fraser was absent at the time. The Lenape chief
Custaloga assisted the French by capturing and handing over two traders who had just arrived at the trading post. Fraser and his employee William were forced to flee, and 75 French soldiers took over Fraser's cabin, allowing Custaloga to confiscate Fraser's trade goods. Fraser's cabin was occupied by Joncaire. By the next year Fraser's cabin and his forge had been incorporated by the French into the new
Fort Machault. Joncaire met with Washington,
Guyasuta, and
Tanacharison on December 4, 1753. Joncaire directed Washington to his superior officer at
Fort LeBoeuf but informed Washington during a dinner that "he had the Command of the Ohio." ==Later life==