Fort Jefferson was a fortification erected by soldiers of the United States Army in October 1791 during the Northwest Indian War.

"[3] Before St. Clair's army departed the fort, a court-martial was conducted for an unknown crime; the three soldiers who were convicted and hanged became the first whites to be executed in present-day Darke County.

This raid began on 25 June 1792, with an attack of one hundred warriors against a party gathering hay for the fort's supplies, and left sixteen soldiers dead or missing.

[2]: 579 The fort came under siege intermittently for three years, as continued Native American attacks were made to neutralize the outpost.

[3] As the United States Army prepared to return to the offensive in the western Ohio country, Fort Jefferson became more than an isolated location outside of the control of the hostile Miamis: projections were created of using the fort as a base for the protection of local settlers and for raids on nearby Native Americans.