Dugué, while commandant of Fort de Chartres, conveys land nearby to his nephew, Ste. Therese Langlois, who founds the town of Prairie du Rocher ("Prairie of the Rock") on the site.

The town is one of the oldest French colonial communities to survive into the twenty-first century in the American Midwest.

Pierre Dugué de Boisbriand leads an expedition to the area south of present-day St. Louis in 1719.

Eighteen miles north of the Jesuit mission at Kaskaskia, he establishes an outpost that he names Fort de Chartres.

The fort will become the center of military and civilian activity in the area known as Upper Louisiana and the Illinois Country.

The French government had granted a trade monopoly to John Law and his Company of the West  on January 1, 1718.

Hoping to make a fortune mining precious metals, the company has built Fort de Chartres to protect its interests.

Dugué, a cousin and fellow officer of brothers (Jean-Baptiste Le Moyne de Bienville and Pierre Le Moyne d'Iberville), with whom he served on expeditions during French colonization in North America, is the son of Michel-Sidrac Dugué de Boisbriand and Marie Moyen Des Granges.

As a French military officer, Dugué holds a succession of posts from 1699 to 1726 at France's settlements on the Gulf Coast and on the Mississippi River in present-day Illinois.

He serves at various times as commander of outposts at Mobile, Natchez, Louisiana, and the area known as the Illinois Country during his military career.

Pierre Dugué de Boisbriand reports in 1720 that the Paniassas, or Black Pawnees, had recently captured a hundred Apaches, whom they were burning, a few each day.

Jean-Baptiste Bénard de la Harpe plans to establish French trading posts at the mouth of the Canadian River and elsewhere in Caddoan territory, but this will not be done and the Pawnee will remain dependent on infrequent and casual traders, while their enemies—the Osages—will benefit from a regular trade.