Many French - speaking residents of Cahokia and elsewhere in what had been Upper Louisiana left rather than live under British rule .
In the treaty ending the war , France ceded large parts of what it called the Illinois Country to the victors .
Many France - speaking residents of Cahokia and elsewhere in what had been Illinois Country   left rather than live under British rule .
In the treaty ending the war , France ceded large parts of what it called the Illinois Country to the victors .