 The area became part of the United States following its conquest during the American Revolutionary War . Veterans of the revolution received land grants in the eastern part of the county as part of Clark 's Grant . Daniel Boone and his brother Squire Boone were early explorers of the county , entering from Kentucky in the 1780s . Harvey Heth , Spier Spencer , and Edward Smith were among the first to settle in the county beginning in the 1790s . Smith built the first home in what later became the county seat of Corydon . 
