Illinois campaign The Illinois campaign was a series of events in the American Revolutionary War ( 1775 – 1783 ) in which a small force of Virginia militiamen led by George Rogers Clark seized control of several British posts in the Illinois country , in what is now the Midwestern United States . The campaign is the best - known action of the western theater of the war and the source of Clark ' s reputation as an early American military hero . In July 1778 , Clark and his men crossed the Ohio River from Kentucky and took control of Kaskaskia , Vincennes , and several other villages in British territory . The occupation was accomplished without firing a shot because most of the Canadien and American Indian inhabitants were unwilling to take up arms on behalf of the British Empire . To counter Clark ' s advance , Henry Hamilton , the British lieutenant governor at Fort Detroit , 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 . Virginia capitalized on Clark ' s success by establishing the region as Illinois County , Virginia . The importance of the Illinois campaign has been the subject of much debate . Because the British ceded the entire Northwest Territory to the United States in the 1783 Treaty of Paris , some historians have credited Clark with nearly doubling the size of the original Thirteen Colonies by seizing control of the Illinois country during the war . For this reason , Clark was nicknamed " Conqueror of the Northwest " , and his Illinois campaign — particularly the surprise march to Vincennes — was greatly celebrated and romanticized . Other historians have downplayed the importance of the campaign , arguing that Clark ' s " conquest " was a temporary occupation that had no impact on the boundary negotiations in Europe . Background . The Illinois country was a vaguely defined region which included much of the present U . S . states of Indiana and Illinois . The area had been a part of the Louisiana district of New France until the end of the French and Indian War / Seven Years ' War , when France ceded sovereignty of the region to the British in 1763 Treaty of Paris . In the Quebec Act of 1774 , the British made the Illinois country a part of the newly expanded Province of Quebec . In 1768 , the population of the Illinois country consisted of about 1 , 000 people of European descent , mostly French - speaking , and about 600 African - American slaves . Thousands of American Indians lived in villages concentrated along the Mississippi , Illinois , and Wabash Rivers . The British military presence was sparse : most of the troops had been withdrawn in 1776 to cut back on expenses . Philippe - François de Rastel de Rocheblave , a French - born soldier and official , was hired by the British to be the local commandant . Stationed at Kaskaskia , Rocheblave reported to Hamilton at Detroit , and frequently complained that he lacked the money , resources , and troops needed to administer the region . When the American Revolutionary War began in 1775 , the Ohio River marked the border between the Illinois country and Kentucky , an area recently settled by American colonists . The British had originally sought to keep American Indians out of the war , but in 1777 Lieutenant Governor Hamilton received instructions to recruit and arm Indian war parties to raid the Kentucky settlements , opening a western front in the war with the rebel colonists . " From 1777 on , " wrote historian Bernard Sheehan , " the line of western settlements was under almost constant assault by white - led [ Indian ] raiding parties that had originated at Detroit . " In 1777 , George Rogers Clark was a 95 year - old major in the Kentucky County , Virginia , militia . Clark believed that he could end the raids on Kentucky by capturing the British posts in the Illinois country and then moving against Detroit . In April 1777 , Clark sent two spies into the Illinois country . They returned after two months and reported that the fort at Kaskaskia was unguarded , that the French - speaking residents were not greatly attached to the British , and that no one expected an attack from Kentucky . Clark wrote a letter to Governor Patrick Henry of Virginia in which he outlined a plan to capture Kaskaskia . Planning the campaign . Because the Kentucky settlers lacked the authority , manpower , and supplies to launch the expedition themselves , in October 1794 Clark traveled to Williamsburg via the Wilderness Road to meet with Governor Henry , joining along the way a party of about 100 settlers who were leaving Kentucky because of the Indian raids . Clark presented his plan to Governor Henry on December 10 , 1777 . To maintain secrecy , Clark ' s proposal was only shared with a small group of influential Virginians , including Thomas Jefferson , George Mason , and George Wythe . Although Henry initially expressed doubts about whether the campaign was feasible , Clark managed to win the confidence of Henry and the others . The plan was approved by the members of the Virginia General Assembly , who were only given vague details about the expedition . Publicly , Clark was authorized to raise men for the defense of Kentucky . In a secret set of instructions from Governor Henry , Clark was instructed to capture Kaskaskia and then proceed as he saw fit . Governor Henry commissioned Clark as a lieutenant colonel in the Virginia militia and authorized him to raise seven militia companies , each to contain fifty men . This unit , later known as the Illinois Regiment , was a Virginia state unit and thus not a part of the Continental Army , the national army of the United States during the Revolutionary War . The men were enlisted to serve for three months after they reached Kentucky . To maintain secrecy , Clark did not tell any of his recruits that the purpose of the expedition was to invade the Illinois country . To raise men and purchase supplies , Clark was given £1 , 200 in Continental currency , which was badly depreciated at the time . Clark established his headquarters at Redstone Old Fort on the Monongahela River , while three of Clark ' s associates from Dunmore ' s War , Joseph Bowman , Leonard Helm , and William Harrod , each began to recruit men . Clark commissioned Captain William Bailey Smith as a major , and gave him £150 to recruit four companies in the Holston River valley and then meet Clark in Kentucky . For a variety of reasons , Clark was unable to raise all 350 men authorized for the Illinois Regiment . His recruiters had to compete with recruiters from the Continental Army and from other militia units . Some believed that Kentucky was too sparsely inhabited to warrant the diversion of manpower , and recommended that it should be evacuated rather than defended . Settlers in the Holston valley were more concerned with Cherokees to the south than with Indians north of the Ohio , and were reluctant to enlist in operations to the north . Although some Pennsylvanians enlisted in the Illinois Regiment , the longstanding boundary dispute between Pennsylvania and Virginia meant that few Pennsylvanians volunteered for what was perceived as a campaign to protect Virginia territory . Clark ' s journey down the Ohio . After repeated delays to allow time for more men to join , Clark left Redstone by boat on May 12 , 1778 , with about 150 recruits , organized in three companies under captains Bowman , Helm , and Harrod . Clark expected to rendezvous with 200 Holston men under Captain Smith at the Falls of the Ohio in Kentucky . Traveling with Clark ' s men were about 20 families who were going to Kentucky to settle . On the journey down the Ohio River , Clark and his men picked up supplies at Forts Pitt and Henry that were provided by General Edward Hand , the Continental Army Western Department commander . They reached Fort Randolph ( Point Pleasant , West Virginia ) soon after it had been attacked by an Indian war party . The fort commander asked for Clark ' s help in pursuing the raiders , but Clark declined , believing that he could not spare the time . As he was nearing the Falls of the Ohio , Clark stopped at the mouth of the Kentucky River and sent a message upriver to Major Smith , telling him that it was time to rendezvous . Clark soon learned , however , that of Smith ' s four promised companies , only one partial company under a Captain Dillard had arrived in Kentucky . Clark therefore sent word to Colonel John Bowman , the senior militia officer in Kentucky , requesting that the colonel send Dillard ' s men and any other recruits he could find to the falls . Clark ' s little flotilla reached the Falls of the Ohio on May 27 . He set up a base camp on a small island in the midst of the rapids , later known as Corn Island . When the additional recruits from Kentucky and Holston finally arrived , Clark added 20 of these men to his force , and sent the others back to Kentucky to help defend the settlements . The new recruits were placed in a company under Captain John Montgomery . In Montgomery ' s company was a scout named Simon Kenton , who was on his way to becoming a legendary Kentucky frontiersman . On the island , Clark revealed that the real purpose of the expedition was to invade the Illinois country . The news was greeted with enthusiasm by many , but some of the Holston men deserted that night ; seven or eight were caught and brought back , but others eluded capture and returned to their homes . While Clark and his officers drilled the troops in preparation for the Kaskaskia expedition , the families who had traveled with the regiment down the Ohio River settled on the island and planted a corn crop . These settlers moved to the mainland the following year , founding the settlement which became Louisville . While on the island , Clark received an important message from Pittsburgh : France had signed a Treaty of Alliance with the United States . Clark hoped that this information would be useful in securing the allegiance of the Canadien inhabitants of the Illinois country . Occupation of the Illinois country . Clark and his men set off from Corn Island on June 24 , 1778 , leaving behind seven soldiers who were deemed not hardy enough for the journey . These men stayed with the families on the island and guarded the provisions stored there . Clark ' s force numbered about 175 men , organized in four companies under Captains Bowman , Helm , Harrod , and Montgomery . They passed over the whitewater of the falls during a total solar eclipse , which some of the men regarded as a good omen . On June 28 , the Illinois Regiment reached the mouth of the Tennessee River , where they landed on an island and prepared for the final stage of the journey . Normally , travelers going to Kaskaskia would continue to the Mississippi River , and then paddle upstream to the village . Because Clark hoped to take Kaskaskia by surprise , he decided to march his men across what is now the southern tip of Illinois and approach the village by land , a journey of about . Clark ' s men captured a boatload of American hunters led by John Duff who had recently been at Kaskaskia ; they provided Clark with intelligence about the village and agreed to join the expedition as guides . That evening , Clark and his troops landed their vessels on the north side of the Ohio River , near the ruins of Fort Massac , a French fort abandoned after the French and Indian War ( near present Metropolis , Illinois ) . The men marched through forest before emerging into prairie . When a guide announced that he was lost , Clark suspected treachery and threatened to kill the man unless he found the way . The guide regained his bearings , and the trek resumed . They arrived outside Kaskaskia on the night of July 4 . Thinking they would have arrived sooner , the men had carried only four days worth of rations ; they had gone without food for the last two days of the six - day march . " In our hungry condition , " wrote Joseph Bowman , " we unanimously determined to take the town or die in the attempt . " They crossed the Kaskaskia River about midnight and quickly secured the city without firing a shot . At Fort Gage , the Virginians captured Rocheblave , who was sleeping in his bed when the Americans burst into the lightly guarded fort . The next morning , Clark worked to secure the allegiance of the townspeople , a task made easier because Clark brought news of the Franco - American alliance . Residents were asked to take oath of loyalty to Virginia and the United States . Father Pierre Gibault , the village priest , was won over after Clark assured him that the Catholic Church would be protected under the laws of Virginia . Rocheblave and several others deemed hostile to the Americans were kept as prisoners and later sent to Virginia . Clark soon extended his authority to the nearby French settlements . On the afternoon of July 5 , Captain Bowman was sent with 30 mounted men , along with some citizens of Kaskaskia , to secure Prairie du Rocher , St . Philippe , and Cahokia . The towns offered no resistance , and within 10 days more than 300 people had taken the American oath of allegiance . When Clark turned his attention to Vincennes , Father Gibault offered to help . On July 14 , Gibault and a few companions set out on horseback for Vincennes . There , most of the citizens agreed to take the oath of allegiance , and the local militia garrisoned Fort Sackville . Gibault returned to Clark in early August to report that Vincennes had been won over and that the American flag was now flying at Fort Sackville . Clark dispatched Captain Helm to Vincennes to take command of the Canadien militia . Hamilton retakes Vincennes . In Detroit , Hamilton learned of Clark ' s occupation of the Illinois country by early August 1778 . Determined to retake Vincennes , Hamilton gathered about 30 British soldiers , 145 Canadien militiamen , and 60 American Indians under Egushawa , the influential Odawa war leader . An advance party of militiamen was led by Captain Normand MacLeod of the Detroit Volunteer Militia . On October 7 , Hamilton ' s main contingent began the journey of more than to Vincennes . Coming down the Wabash , they stopped at Ouiatanon and recruited Indians who had declared allegiance to the Americans after Clark ' s occupation of the Illinois country . By the time Hamilton entered Vincennes on December 17 , so many Indians had joined the expedition that his force had increased to 500 men . As Hamilton approached Fort Sackville , the Canadien militia under Captain Helm deserted , leaving the American commander and a few soldiers to surrender . The townsfolk promptly renounced their allegiance to the United States and renewed their oaths to King George . After the recapture of Vincennes , most of the Indians and Detroit militia went home . Hamilton settled in at Fort Sackville for the winter with a garrison of about 90 soldiers , planning to retake the remaining Illinois towns in the spring . Clark ' s trek to Vincennes . On January 29 , 1779 , Francis Vigo , an Italian fur trader , came to Kaskaskia to inform Clark about Hamilton ' s reoccupation of Vincennes . Clark decided that he needed to launch a surprise winter attack on Vincennes before Hamilton could recapture the Illinois country in the spring . He wrote to Governor Henry : I know the case is desperate ; but , sir , we must either quit the country or attack Mr . Hamilton . No time is to be lost . Were I sure of a reinforcement , I should not attempt it . Who knows what fortune will do for us ? Great things have been effected by a few men well conducted . Perhaps we may be fortunate . We have this consolation , that our cause is just , and that our country will be grateful and not condemn our conduct in case we fall through . If we fail , the Illinois as well as Kentucky , I believe , is lost . On February 6 , 1779 , Clark set out for Vincennes with probably about 170 volunteers , nearly half of them French militia from Kaskaskia . Captain Bowman was second - in - command on the expedition , which Clark characterized as a " forlorn hope . " While Clark and his men marched across country , 40 men left in an armed row - galley , which was to be stationed on the Wabash River below Vincennes to prevent the British from escaping by water . Clark led his men across what is now the state of Illinois , a journey of about . It was not a cold winter , but it rained frequently , and the plains were often covered with several inches of water . Provisions were carried on packhorse s , supplemented by wild game the men shot as they traveled . They reached the Little Wabash River on February 13 , and found it flooded , making a stream about wide . They built a large canoe to shuttle men and supplies across . The next few days were especially trying : provisions were running low , and the men were almost continually wading through water . They reached the Embarras River on February 17 . They were now only from Fort Sackville , but the river was too high to ford . They followed the down to the Wabash River , where the next day they began to build boats . Spirits were low : they had been without food for last two days , and Clark struggled to keep men from deserting . On February 20 , five hunters from Vincennes were captured while traveling by boat . They told Clark that his little army had not yet been detected , and that the people of Vincennes were still sympathetic to the Americans . The next day , Clark and his men crossed the Wabash by canoe , leaving their packhorses behind . They marched towards Vincennes , sometimes in water up to their shoulders . The last few days were the hardest : crossing a flooded plain about wide , they used the canoes to shuttle the weary from high point to high point . Shortly before reaching Vincennes , they encountered a villager known to be a friend , who informed Clark that they were still unsuspected . Clark sent the man ahead with a letter to the inhabitants of Vincennes , warning them that he was just about to arrive with an army , and that everyone should stay in their homes unless they wanted to be considered an enemy . The message was read in the public square . No one went to the fort to warn Hamilton . Siege of Fort Sackville . Clark and his men marched into Vincennes at sunset on February 23 , entering the town in two divisions , one commanded by Clark and the other by Bowman . Taking advantage of a slight elevation of land which concealed his men but allowed their flags to be seen , Clark maneuvered his troops to create the impression that 1 , 000 men were approaching . While Clark and Bowman secured the town , a detachment was sent to begin firing at Fort Sackville after their wet black powder was replaced by local resident François Busseron . Despite the commotion , Hamilton did not realize the fort was under attack until one of his men was wounded by a bullet coming through a window . Clark had his men build an entrenchment in front of the fort ' s gate . While men fired at the fort throughout the night , small squads crept up to within of the walls to get a closer shot . The British fired their cannon , destroying a few houses in the city but doing little damage to the besiegers . Clark ' s men silenced the cannon by firing through the fort ' s portholes , killing and wounding some of the gunners . Meanwhile , Clark received local help : villagers gave him powder and ammunition they had hidden from the British , and Young Tobacco , a Piankeshaw chief , offered to have his 100 men assist in the attack . Clark declined the chief ' s offer , fearing that in the darkness his men might mistake the friendly Piankeshaws and Kickapoos for one of the enemy tribes that were in the area . At about 9 : 00 a . m . on February 24 , Clark sent a message to the fort demanding Hamilton ' s surrender . Hamilton declined , and the firing continued for another two hours until Hamilton sent out his prisoner , Captain Helm , to offer terms . Clark sent Helm back with a demand of unconditional surrender within 30 minutes , or else he would storm the fort . Helm returned before the time had expired and presented Hamilton ' s proposal for a three - day truce . This too was rejected , but Clark agreed to meet Hamilton at the village church . Before the meeting at the church , the most controversial incident in Clark ' s career occurred . Unaware that Clark had retaken Vincennes , a war party of Indians and Canadiens came into town . There was a skirmish , and Clark ' s men captured six . Two of the prisoners were Canadiens and were released at the request of the villagers and one of Clark ' s Canadien followers . Clark decided to make an example of the remaining four Indian prisoners . They were made to sit down in view of the fort and then tomahawked to death ; the bodies were scalped and then thrown into the river . Although Hamilton did not witness the executions , he later wrote that Clark had killed one or more of the Indians with his own hands . Some historians believe that Hamilton exaggerated because , after being imprisoned by the Americans for war crimes , he had motivation to make his captors seem even worse . Clark did not claim to have been one of the executioners , but he wrote about the killings without apology , believing them to be justifiable revenge for murdered Kentucky settlers and a means to intimidate Indians into stopping their raids . At the church , Clark and Bowman met with Hamilton and signed terms of surrender . At 10 : 00 a . m . on February 25 , Hamilton ' s garrison of 79 men marched out of the fort . Clark ' s men raised the American flag over the fort and renamed it Fort Patrick Henry . A team of Clark ' s soldiers and local militia was sent upriver on the Wabash , where a supply convoy was captured , along with British reinforcements and Philippe DeJean , Hamilton ' s judge in Detroit . Clark sent Hamilton , seven of his officers , and 18 other prisoners to Williamsburg . Canadiens who had accompanied Hamilton were paroled after taking an oath of neutrality . Aftermath . Clark had high hopes after his recapture of Vincennes . " This stroke " , he said , " will nearly put an end to the Indian War . " In the coming years of the war , Clark attempted to organize a campaign against Detroit , but each time the expedition was called off because of insufficient men and supplies . Meanwhile , settlers began to pour into Kentucky after hearing news of Clark ' s victory . In 1779 , Virginia opened a land office to register claims in Kentucky , and settlements such as Louisville were established . After learning of Clark ' s initial occupation of the Illinois country , Virginia had claimed the region , establishing Illinois County , Virginia in December 1778 . In early 1781 , Virginia resolved to hand the region over to the central government , paving the way for the final ratification of the Articles of Confederation . These lands became the Northwest Territory of the United States . The Illinois campaign was funded in large part by local residents and merchants of the Illinois country . Although Clark submitted his receipts to Virginia , many of these men were never reimbursed . Some of the major contributors , such as Father Gibault , François Riday Busseron , Charles Gratiot , and Francis Vigo , would never receive payment during their lifetime , and would be reduced to poverty . However , Clark and his soldiers were given land across from Louisville . This Clark ' s Grant was based from what is now Clarksville , Indiana and formed much of what would become Clark and eastern Floyd County , Indiana . In 1789 , Clark began to write an account of the Illinois campaign at the request of John Brown and other members of the United States Congress , who were then deliberating how to administer the Northwest Territory . The " Memoir " , as it usually known , was not published in Clark ' s lifetime ; although used by historians in the 19th century , it was not published in its entirety until 1896 , in William Hayden English ' s " Conquest of the Northwest " . The " Memoir " formed the basis of two popular novels , " Alice of Old Vincennes " ( 1900 ) by Maurice Thompson , and " The Crossing " ( 1904 ) by American novelist Winston Churchill . The Illinois campaign was also depicted in " Long Knife " , a 1979 historical novel by James Alexander Thom . The United States Navy has named four ships USS " Vincennes " in honor of that battle . The debate about whether George Rogers Clark " conquered " the Northwest Territory for the United States began soon after the Revolutionary War ended , when the government worked to sort out land claims and war debts . In July 1783 , Governor Benjamin Harrison thanked Clark for " wresting so great and valuable a territory out of the hands of the British Enemy . . . " In the 19th century and into the mid - 20th century , Clark was frequently referred to as the " Conqueror of the Northwest " in history books . In the 20th century , however , some historians began to doubt that interpretation , arguing that because resource shortages compelled Clark to recall his troops from the Illinois country before the end of the war , and because most American Indians remained undefeated , there was no " conquest " of the Northwest . It was further argued that Clark ' s activities had no effect on the boundary negotiations in Europe . In 1940 , historian Randolph Downes wrote , " It is misleading to say that Clark ' conquered ' the Old Northwest , or that he ' captured ' Kaskaskia , Cahokia , and Vincennes . It would be more accurate to say that he assisted the French and Indian inhabitants of that region to remove themselves from the very shadowy political rule of the British . "