 After the outbreak of the American Revolutionary War, George Rogers Clark was sent from Virginia to enforce its claim to much of the land in the Great Lakes region.In July 1778, Clark and about 175 men crossed the Ohio River and took control of Kaskaskia, Cahokia, and Vincennes, along with several other villages in British Indiana.The occupation was accomplished without firing a shot because Clark carried letters from the French ambassador stating that France supported the Americans.