George Rogers Clark was a surveyor and soldier from Virginia who became the highest-ranking American military officer on the northwestern frontier during the Revolutionary War. He spent most of the war as the leader of the Kentucky militia, which was then part of Virginia. Clark is best known for his celebrated captures of Kaskaskia and Vincennes during the 1778–1779 Illinois campaign. These crucial victories severely weakened British influence in the region and were instrumental in the United States acquiring the Northwest Territory.