The cantonment had its inception in a late 1790s diplomatic crisis between the United States and France. The French had begun seizing American ships on the high seas and it appeared that all-out war was imminent. In response, George Washington and Alexander Hamilton developed a plan for a large American military base or cantonment in the Ohio River valley. Once the war started, troops from this “Reserve Corps” would move into the Mississippi River Valley and capture the river and New Orleans and from the Spanish who were expected to ally themselves with the French.
The contonment was established by Lieutenant Colonel David Strong in 1797 as a post of the United States Army. General James Wilkinson (1757-1825) was put in charge of this operation despite rumors that he was a traitor in the pay of the Spanish Government as "Agent № 13," known as the "Spanish Conspiracy."
Wilkinson ordered smaller posts such as Fort Massac to be abandoned and added their garrisons to the Reserve Corps. Commonly alleged is that Wilkinson actually plotted with the Spanish for their seizure of Fort Massac (Metropolis, Illinois) in the so‑called "Tom Powers Plot."
On November 14, 1801 Lewis and Clark deliberately passed the fort on the far side of the river and did not stop because they were worried about the motives of General Wilkinson being a conspirator for the Spanish.
|General James Wilkinson|
Some 500 to as many as 1500 men were stationed here during the period of 1798-1805, which was commonly called Fort Wilkinsonville.
As this description indicates, the cantonment was essentially a large camp of huts and other buildings used by the Army. The camp lacked a stockade wall with the boundaries of the camp instead patrolled by sentinels. Other features of the cantonment included quarter master supply buildings, hospital, bakery, brick works, powder magazine, commanding officer’s quarters, vegetable gardens, parade grounds, a boat yard and a log palisade enclosing the compound. About 400 acres were cleared with the site overlooking the Ohio River at the head of the Grand Chain of Rocks, about 14 miles above the confluence of the Ohio and Mississippi Rivers.
The cantonment reached its peak strength in summer, 1801, when it contained approximately 1,500 soldiers and an unknown number of civilians including laundresses, nurses, sutlers (peddlers), and boat men. During this same time a deadly illness struck the cantonment with a reported 70 soldiers dying from what appears to have been a combination of malaria and dysentery. These soldiers and the base commander Lt. Col. Strong, who died of an unrelated illness, were buried in the cantonment cemetery, the location of which is now unknown.
The majority of the troops moved to the mouth of the Tennessee River following Colonel Strong’s death with Major Jonathon Williams, a grand-nephew of Benjamin Franklin and the later founder of West Point and the U.S. Army Corps of Engineers, left in charge of approximately 70 soldiers including those sick who could not be moved. The 2nd Infantry troops at the mouth of the Tennessee River returned to the cantonment in the fall of 1801, raising the garrison strength to approximately 800 men.
Final abandonment of the cantonment appears to have occurred in April, 1802, following the election of Thomas Jefferson and his subsequent reduction in size of the U.S. Army. Following the departure of the last of the soldiers.
The abandoned structures later became the small community of Wilkinsonville. Approximately 200 Cherokee occupied the abandoned cantonment buildings for several years.
These buildings appear to have gradually collapsed or been destroyed for their wood although scattered accounts exist that indicate the Cherokee burned the buildings. The last known account of still-standing structures at the abandoned cantonment dates to 1817. After that, the abandoned cantonment became the site of a small settlement named Wilkinsonville consisting of no more than a few buildings that appeared on maps throughout the early nineteenth century.
|The marker is located just south of New Grand Chain,|
on the east side of IL Route 37.
Compiled by Neil Gale, Ph.D.
 The The Complete Three Volume Set: "Memoirs of My Own Times" written by General James Wilkinson, published in 1816; in my Digital Research Library of Illinois History®
 In April 1787, Wilkinson made a highly controversial trip to New Orleans, which was the capital of Spanish colonial Louisiana. At that time, Americans were allowed to trade on the Mississippi River, but they had to pay a hefty tariff. Wilkinson met with Spanish Governor Esteban Rodríguez Miró and managed to convince him to allow Kentucky to have a trading monopoly on the River; in return he promised to promote Spanish interests in the west.
On August 22, 1787, Wilkinson signed an expatriation declaration and swore allegiance to the King of Spain to satisfy his own commercial needs. The "Spanish Conspiracy," as it is known, was initiated by Wilkinson's "First Memorial," a 7,500-word report written before he left New Orleans for Charleston, to the Spanish concerning the "political future of western settlers," and to convince Spain to "admit us [Kentuckians] under protection as vassals (a person or country in a subordinate position to another.)." This was encoded with myriad symbols, numbers, and letters that was decoded via a complex English-Spanish cipher code-named "Number 13," which became the basis for his pseudonym, "Agent № 13."
Upon returning to Kentucky in February 1788, Wilkinson vigorously opposed the new U.S. Constitution. Kentucky had nearly achieved statehood under the old Articles of Confederation, and there was widespread disappointment when this was delayed because of the new constitution.
When the United States government reorganized the Army as the Legion of the United States, President George Washington was faced with the decision of whom to name as its commanding general. The two major candidates for this promotion were James Wilkinson and Anthony Wayne. In the end, the cabinet chose Wayne due to Wilkinson's suspected involvement with the Spanish government. The cabinet promoted Wilkinson to brigadier general as consolation, since President Washington was aware of Wilkinson's fragile ego.
Wilkinson developed a jealousy of Wayne, but he maintained an ostensible (stated or appearing to be true, but not necessarily so) respect toward the general. However, when Wayne wasn't invited to Wilkinson's Christmas party, Wayne developed a full-fledged hatred for Wilkinson, deeming it to be an act of disrespect.
Wilkinson proceeded to file formal complaints with President Washington, against Wayne and his decisions. Upon finding out about the complaints against him, Wayne decided to fight back, launching an investigation into Wilkinson's history with the Spanish. During all of this time, Wilkinson had renewed his secret alliance with the Spanish government (through the Governor of Louisiana Francisco Luis Héctor de Carondelet), alerting them to the actions of both the U.S. and the French occupancy in North America. When Spanish couriers were intercepted carrying payments for Wilkinson, Wayne's suspicions were confirmed and he attempted to court martial Wilkinson for his treachery. However, Wayne developed a stomach ulcer and died on December 15, 1796.
 Some historical references seem to confuse Fort Massac and Cantonment Wilkinson. Fort Massac is a state park in the west edge of Metropolis, also along the Ohio River. The two are separated by about 15 miles.
 Under this plan Fort Massac was to be taken by the Spanish and mounted with twenty guns. The plotters were also to have a sum of $100,000 for raising and maintaining forces there.