on September 8, Cornwallis withdrew to Charleston with little to show for his campaign. Western campaign From the beginning of the war, Bernardo de Gálvez, the Governor of Spanish Louisiana, allowed the Americans to import supplies and munitions into New Orleans, then ship them to Pittsburgh. This provided an alternative transportation route for the Continental Army, bypassing the British blockade of the Atlantic Coast. The trade was organized by Oliver Pollock, a successful merchant in Havana and New Orleans who was appointed US "commercial agent". It also helped support the American campaign in the west; in the 1778 Illinois campaign, militia under General George Rogers Clark. In February 1778, an expedition of militia to destroy British military supplies in settlements along the Cuyahoga River was halted by adverse weather. Later in the year, a second campaign was undertaken to seize the Illinois Country from the British. Virginia militia, Canadien settlers, and Indian allies commanded by Colonel George Rogers Clark captured Kaskaskia on July 4 then secured Vincennes, though Vincennes was recaptured by Quebec Governor Henry Hamilton. In early 1779, the Virginians counter-attacked in the siege of Fort Vincennes and took Hamilton prisoner. Clark secured western British Quebec as the American Northwest Territory in the Treaty of Paris concluding the war. When Spain joined France's war against Britain in 1779, their treaty specifically excluded Spanish military action in North America. Later that year, however, Gálvez initiated offensive operations against British outposts. First, he cleared British garrisons in Baton Rouge, Louisiana, Fort Bute, and Natchez, Mississippi, and captured five forts. In doing so, Gálvez opened navigation on the Mississippi River north to the American settlement in Pittsburg. On May 25, 1780, British Colonel Henry Bird invaded Kentucky as part of a wider operation to clear American resistance from Quebec to the Gulf coast. Their Pensacola advance on New Orleans was overcome by Spanish Governor Gálvez's offensive on Mobile. Simultaneous British attacks were repulsed on St. Louis by the Spanish Lieutenant Governor de Leyba, and on the Virginia county courthouse at Cahokia by Lieutenant Colonel Clark. The British initiative under Bird from Detroit was ended at the rumored approach of Clark. The scale of violence in the Licking River Valley, was extreme "even for frontier standards." It led to men of English and German settlements to join Clark's militia when the British and their hired German soldiers withdrew to the Great Lakes. The