The fertile prairies of Illinois drew the attention of French trader Louis Jolliet and Father Jacques Marquette as they explored the Mississippi and Illinois Rivers in 1673. France claimed the region until 1763, when it surrendered it to Great Britain by the Treaty of Paris. During the American Revolution, George Rogers Clark and his small army won a bloodless victory by capturing Kaskaskia for the Commonwealth of Virginia, and Illinois then became a county of Virginia. The area was ceded to the United States in 1784 and became part of the Northwest Territory and the Indiana Territory before a separate Illinois Territory was created. On December 3, 1818, Illinois entered the Union as the twenty-first state. The fourteen northern counties of Illinois, including the site of Chicago, were added to the state through the foresight of Nathaniel Pope, congressional delegate from the Illinois Territory, whose amendment to the statehood act moved the upper boundary from an east-west line through the tip of Lake Michigan to its present location. Before the first settlers arrived, lands in this vicinity were hunting grounds for the Potawatomi Indians, who traded furs with hunters coming up the Fox River. Lake Zurich was founded by Seth Paine, an abolitionist and free-thinker who settled there in 1836 and built a structure he called a "Stable of Humanity," containing a meeting hall, school, and store and providing lodging for unfortunate families. At one time Paine regarded all civil law, including marriage and taxes, as a form of slavery, and later he went to Chicago, where he continued his philanthropy.