Pierre Joseph Céloron de Blainville
Celeron de Bienville led an expedition to advance France's territorial claim on the Ohio Valley.
Background
From 1743 to 1748, England and France fought King George's War. During this war, Great Britain blockaded New France. This inhibited their fur trade with Native Americans because they lacked trade goods. British traders became the major trading partners with Native Americans in the Ohio valley.
France claimed the Ohio Valley (and indeed the entire Mississippi basin) on the basis of the explorations made by La Salle in 1669 and 1682. Great Britain claimed the Ohio Valley on the basis of purchases from Native Americans in 1744. In fact, both the colonies of Virginia and Pennsylvania had claims on the Ohio valley, although in the 1740s and 1750s, it was Virginia that was more active in pressing her claim.
The Expedition
In 1748, Comte de la Galissoniere, the governor of New France, ordered Celeron de Bienville (also known as Celeron de Blainville) to strengthen the French claim on the Ohio Valley. De Bienville carried out this mission in the summer of 1749. The expedition set out from Montreal on June 15, 1749, in a flotilla consisting of large boats and canoes. The expedition included 216 French and Canadians and 55 Native Americans. On 1749-07-29, the expedition reached the Allegheny River, and began to descend it.
As it progressed, the expedition sought to strengthen France's claim to the territory by marking it at the mouths of principal tributaries. They did this by nailing a copper plate bearing the French royal arms to a tree, and burying an inscribed leaden plate. This was a traditional European mode of marking territory, but it might have contributed to Native American anxieties about the intentions of the French, and thus ultimately had a counterproductive effect.
When de Bienville arrived at Logstown, he discovered some English traders there. Incensed, he evicted the traders and wrote a scolding note to the governor of Pennsylvania. He then hectored the Native Americans about French dominance of the region. The expulsion of the British traders and the hectoring offended the Iroquois in his party, some of whom returned to their homeland in present-day New York, tearing down some of the copper plates as they went.
The party then preceded past the current site of Pittsburgh, and down the Ohio River. A plate was buried at the mouth of the Kanawha River on 1749-08-18.
In the Lower Shawnee Town at the Scioto River's mouth, he again encountered English traders. De Bienville demanded that the English leave, but most refused.
Five months after the expedition began, it returned to Montreal, arriving 1749-11-10.
In total, De Bienville buried at least six plates. Only two have ever been found. His journal is archived at Archieves of the Department de la Marine, Paris, France.
The French continued to press their claim to the Ohio Valley, leading to the Seven Year's War.