|Signed||September 30, 1809|
|Location||Fort Wayne, Indiana Territory|
|Condition||Transfer of money and goods to natives; Natives to allow American settlement of purchased land; Contingent on the later acceptance of the Kickapoo and Wea.|
|Signatories||William Henry Harrison, Native leaders|
|Parties||United States of America, Delawares, Potowatomi, Miami, The Eel River band of Miami, Weas (Signed November 1809), Kickapoo (Signed March 1810).|
The Treaty of Fort Wayne, sometimes called the Ten O'clock Line Treaty or the Twelve Mile Line Treaty, is an 1809 treaty that obtained 3,000,000 acres (approximately 12,000 km²) of American Indian land for the white settlers of Illinois and Indiana. The tribes involved were the Delaware and others. The negotiations excluded the Shawnee who were minor inhabitants of the area and had been asked to leave the area previously by Miami War Chief Little Turtle. Territorial Governor William Henry Harrison negotiated the treaty with the tribes. The treaty led to a war with the United States begun by Shawnee leader Tecumseh and other dissenting tribesmen in what came to be called " Tecumseh's War".
The treaty also has two nicknames, the "Ten O'clock Line Treaty of 1809" and the "Twelve Mile Line Treaty" associated with the disparate parcels of land defined by the treaty. The first nickname comes from tradition that says the Native Americans did not trust the surveyors' equipment, so a spear was thrown down at ten o'clock and the shadow became the treaty line. There are other myths that say it was either a tree or a fence that was used.[ citation needed] The Twelve Mile Line was a reference to the Greenville Treaty and the establishment of a new 'line' parallel to it but twelve miles further west.
In 1809 Harrison began to push for a treaty to open more land for settlement. The Miami, Wea, and Kickapoo were "vehemently" opposed to selling any more land around the Wabash River.  In order to influence those groups to sell the land, Harrison decided, against the wishes of President James Madison, to first conclude a treaty with the tribes willing to sell and use them to help influence those who held out. In September 1809 he invited the Potawatomie, Delaware, Eel Rivers, and the Miami to a meeting in Fort Wayne. In the negotiations Harrison promised large subsidies and payments to the tribes if they would cede the lands for which he was asking. 
Only the Miami opposed the treaty. They presented their copy of the Treaty of Greenville and read the section that guaranteed their possession of the lands around the Wabash River. They then explained the history of the region and how they had invited the Wea and other tribes to settle in their territory as friends. The Miami were concerned the Wea leaders were not present, although they were the primary inhabitants of the land being sold. The Miami also wanted any new land sales to be paid for by the acre, and not by the tract. Harrison agreed to make the treaty's acceptance contingent on approval by the Wea and other tribes in the territory being purchased, but he refused to purchase land by the acre. He countered that it was better for the tribes to sell the land in tracts so as to prevent the Americans from only purchasing their best lands by the acre and leaving them only poor land on which to live. 
After two weeks of negotiating, the Potawatomie leaders convinced the Miami to accept the treaty as reciprocity to the Potawatomie who had earlier accepted treaties less advantageous to them at the request of the Miami. Finally the Treaty of Fort Wayne was signed on September 29, 1809, selling United States over 3,000,000 acres (approximately 12,000 km²), chiefly along the Wabash River north of Vincennes.  During the winter months, Harrison was able to obtain the acceptance of the Wea by offering them a large subsidy and the help of Miami Chief Pacanne who helped to influence the Wea leaders. The Kickapoo were closely allied with the Shawnee at Prophetstown and Harrison feared they would be difficult to sway. He offered the Wea an increased subsidy if the Kickapoo would also accept the treaty, causing the Wea to pressure the Kickapoo leaders to accept. By the spring of 1810 Harrison had completed negotiations and the treaty was finalized. 
In August 1810 Tecumseh, a leader of a breakaway Shawnee group living just north of the area purchased, and 400 armed warriors from several different tribes traveled down the Wabash to meet with Harrison in Vincennes. Tecumseh insisted that the Fort Wayne treaty was illegitimate; he asked Harrison to nullify it and warned that Americans should not attempt to settle the lands sold in the treaty. Tecumseh acknowledged to Harrison that he had threatened to kill the chiefs who signed the treaty if they carried out its terms.   Harrison responded to Tecumseh that the Miami were the owners of the land and could sell it if they so choose. He also rejected Tecumseh's claim that all the Indians formed one nation, and each nation could have separate relations with the United States. 
Before leaving, Tecumseh informed Harrison that unless the treaty was nullified, he would seek an alliance with the British.  The situation continued to escalate leading to the outbreak of hostilities between Tecumseh's followers and settlers later that year. Tensions continued to rise in the following year leading to the Battle of Tippecanoe during a period sometimes called Tecumseh's War.  
- Owens, p. 200
- Owens, p. 201–203
- Owens, p. 205
- Langguth, p. 164
- Owens, p. 212
- Langguth, p. 165
- Langguth, p. 166
- Langguth, p. 167–169
- Owens, p. 214
- Langguth, A. J. (2006). Union 1812:The Americans Who Fought the Second War of Independence. New York: Simon & Schuster. ISBN 0-7432-2618-6.
- Owens, Robert M. (2007). Mr. Jefferson's Hammer: William Henry Harrison and the Origins of American Indian Policy. Norman, Oklahoma: University of Oklahoma Press. ISBN 978-0-8061-3842-8.
- "Treaty text". Oklahoma State University Library. Retrieved 2009-03-06.