Shortly after the Revolutionary War began, Kentucky County, Virginia was organized with George Rogers Clark as head of its local militia. Clark asked Governor Patrick Henry for permission to lead a secret expedition to capture the nearest British posts, which were located in the Illinois country. Governor Henry commissioned Clark as a lieutenant colonel and authorized him to raise troops for the expedition. The Illinois campaign began in July 1778, when Clark and about 175 men crossed the Ohio River at Fort Massac and marched to Kaskaskia, taking it on the night of July 4. Cahokia, Vincennes, and several other villages and forts in British territory were subsequently captured without firing a shot, because most of the French-speaking and American Indian inhabitants were unwilling to take up arms on behalf of the British. To counter Clark's advance, Henry Hamilton reoccupied Vincennes with a small force. In February 1779, Clark returned to Vincennes in a surprise winter expedition and retook the town, capturing Hamilton in the process. The winter expedition was Clark's most significant military achievement.