While the war's main armies fought along the Atlantic seaboard, a separate conflict raged on the frontier west of the Appalachians, where British-supplied raids out of Detroit threatened Kentucky's small settlements. George Rogers Clark, a young Virginia militia officer, proposed striking at the source: capturing the British-held towns of the Illinois country itself. In the summer of 1778 he took Kaskaskia and Cahokia without firing a shot. When the British governor at Detroit, Henry Hamilton, retook the post at Vincennes that winter, Clark marched back to take it a second time, through floodwater that reached his men's chests for the final stretch. Clark's own account of the campaign survives at Founders Online. Hamilton's, written as Clark's prisoner in the weeks that followed, survives in full at the Indiana Historical Bureau, and it does not match the version of events Clark sent home.
Clark left Kaskaskia on February 5 with 172 men, nearly half of them French volunteers from the Illinois towns, on a roughly 180-mile march to Vincennes. Unseasonal flooding had put the countryside under water for miles in every direction, and Clark's own account of the campaign, written to Virginia Governor Patrick Henry that April, described an operation that depended on speed and surprise because his small force could not have survived a prolonged siege.
Having not received a scrape of a pen from you for near twelve months I could see but little probability of keeping possession of the country, as my number of men was too small to stand a siege and my situation too remote to call for assistance. I made all the preparations I possibly could for the attack.
Clark's men surrounded the fort on the night of February 23, undetected by a garrison that had no idea an American force was anywhere near. After a night of exchanged fire, Clark sent a written demand for surrender into the fort the next morning.
I expect you shall immediately surrender yourself with your Garrison prisoners at discretion. If any of the stores be destroyed or any letters or papers burned, you may expect no mercy, for by Heavens you shall be treated as a murderer.
Hamilton refused, telling his officers he intended to defend the fort to the last extremity. But roughly half his garrison was French Canadian militia, several of whom had family and friends already fighting on the American side, and Hamilton recorded that his French troops "hung their heads" rather than cheer the decision. By the next day, with his force effectively split and his position untenable, Hamilton agreed to negotiate.
Hamilton formally surrendered Fort Sackville on February 25. His garrison marched out with their weapons before stacking arms, and Clark's men raised the American flag over the post. Hamilton himself was sent east under guard to Williamsburg, where Virginia's governing council, headed by Thomas Jefferson, ordered him held in irons, a punishment unusually harsh for a surrendered officer, justified at the time by accusations that Hamilton had paid for American scalps delivered by his Native allies, a practice that earned him the nickname "the Hair Buyer" on the frontier. The treatment was eased only after George Washington intervened on Hamilton's behalf months later.
Clark's victory secured Virginia's claim to the Illinois country for the remainder of the war, territory that Britain formally ceded to the United States in the 1783 Treaty of Paris, an outcome that nearly doubled the size of the original thirteen states on paper. Clark spent years afterward trying and failing to organize an expedition against the British stronghold at Detroit itself, never receiving the men or supplies Virginia had promised him.
If you learned something new or just enjoyed the content, please share it and follow along on X and Substack.