George Rogers Clark Memorial, 
Vincennes, Indiana 

George Rogers Clark Day commemorates the day in 1779 when Clark accepted the surrender of Fort Sackville at Vincennes and celebrates his great contributions to the cause of American independence, which include conquering and securing the Northwest Territory and establishing and promoting the first permanent American settlement in the Northwest Territory - Clarksville.

On the morning of February 25, 1779, Lieutenant Colonel George Rogers Clark, elder brother of explorer William Clark, accepted British Lt. Gov. Henry Hamilton's unconditional surrender of Fort Sackville at Vincennes, Indiana. 

Despite a 1763 prohibition against settlement of Kentucky and points west, hundreds of colonists and their families drifted beyond the Appalachians. With the Revolutionary War under way, these pioneers were vulnerable to attack from both British and Native American forces. Clark believed Hamilton rewarded Indians for raids on American settlements. With the support of Virginia's Governor, Patrick Henry, Clark marshalled volunteers from among the frontiersmen and successfully attacked British outposts along the Mississippi River. To capture Fort Sackville, Clark relied on his men's expert marksmanship and a classic military bluff. Although he commanded a mere two hundred buckskin clad pioneers, Clark raised flags enough for a company of 600. Believing himself overwhelmed, Hamilton surrendered and was imprisoned at Williamsburg. The British never regained control of the fort. 

Clark's success was noted by Governor Thomas Jefferson, of Virginia, and General George Washington: 

Sir: On the 4th Instant I had the Honor to receive your Letter of the 19th of June. Your Excellency will permit me to offer you my sincere congratulations upon your appointment to the Government of Virginia. 

I thank you much for the accounts Your Excellency has been pleased to transmit me of the successes of Cols. Clarke and Shelby. They are important and interesting, and do great honor to the Officers and Men engaged in the Enterprises. I hope these successes will be followed by very happy consequences. If Col. Clarke could by any means gain possession of Detroit, it would in all probability effectually secure the friendship or at least the neutrality of most of the Western Indians.
(Letter from George Washington to Thomas Jefferson, July 10, 1779. The George Washington Papers at the Library of Congress)

Clark's bold defense of the trans-Appalachian frontier during the Revolution frustrated British attempts to drive Americans out of the region and legitimized American claims to the Northwest Territory - land ceded to the United States by the Treaty of Paris in 1783. Since the mid-1700s, at least, American colonists under British rule settled land west of the Appalachian Mountains. European control of these lands was claimed first by France. Native American tribes had occupied the lands for generations. France and Great Britain fought the French and Indian War (1754-1763) for control of land and power in North America. The Treaty of Paris - February 10, 1763 - gave the victorious British control of Canada and most land east of the Mississippi River. Over the following years, there was continuing conflict. The British tried to restrict the freedoms of American colonists. American settlers on the western frontier and Indians fought to occupy the land. American settlers and Indians committed atrocities against each other.

Conflicts with the British resulted in the Declaration of Independence on July 4, 1776 and the American Revolution. The Native American tribes were caught in the middle, and both sides sought their allegiance. American officials generally wanted Indian neutrality. After mid-1777, many Indians fought against the Americans to help Great Britain gain control of the frontier. Indians worked for the British for weapons, food, and other supplies.

The British government in the west ruled from Detroit. In 1775 Henry Hamilton became the lieutenant governor of Detroit. He directed Indian raids against American frontier settlements, and Americans generally expressed hatred of him.

In late 1777, George Rogers Clark went from Kentucky County, Virginia to Williamsburg with a plan. Governor Patrick Henry and the Virginia Council agreed publicly to provide money and men to protect the Kentucky settlements from the Indians. Privately - in the secret orders of January 2, 1778 - Clark was authorized to attack British forts in the west-called the Illinois country. The goal was to protect the settlements by gaining control of the area north of the Ohio River. The plan required winning the loyalty of mainly French settlers in the region, gaining the neutrality of Native American tribes, and removing British troops. Clark also wanted to attack Detroit.

In early 1778, Clark went from Williamsburg to Fort Pitt to recruit men and supplies. He then travelled down the Ohio River. At the Falls of the Ohio River, he established his camp in May 1778. Historians generally believe that Clark's successful campaign assured United States possession of the territory north of the Ohio River and east of the Mississippi River in the peace treaty with Great Britain in 1783. The area was formed into the Northwest Territory in 1787.