イリノイ郡
In 1763 the Treaty of Paris was signed following the Seven Years' War (French and Indian War) and the French transferred control of the Illinois Country east of the Mississippi to Great Britain. (Spain had been granted the western part of the Illinois Country—also known as "Upper Louisiana"—in the 1762 Treaty of Fontainebleau.) The stone fort had served as center of French administration of the region for only twenty years.