Fort Knox II was one of several forts built and garrisoned in the Vincennes area to protect settlers and to control the strategic Wabash River during the town's long history as an outpost of frontier settlement. Three of these forts were constructed by the United States government. Each was named Fort Knox after Henry Knox, the first secretary of war. Historically, the forts were not known by their numerical extensions. The numbering has been introduced by more modern historians as a means of easy identification for each Fort Knox. During the three separate periods of existence, each garrison would have been known simply as “Fort Knox.”
The first Fort Knox (1787-1803) was, for a time, the most western post on the far frontier. The original Fort Knox site is identified with a historical marker located at Buntin & 1st streets in downtown Vincennes.
Fort Knox II (1803-1813) was constructed three miles north of Vincennes during an interlude in conflicts with the Indians. For much of its existence, it consisted of only a few buildings without a palisade wall. Today, this former major military location is a part of the Vincennes State Historic Sites (administered by the Indiana Department of Natural Resources).
It was not until 1809, with the growing tensions between Indians and American settlers, that the need for military defenses again became of paramount importance. Later, Fort Knox II was strengthened by the addition of a wall and blockhouse, as the fort and the town of Vincennes became the center of military activity for the Indiana Territory.
During 1813, in order to provide increased protection for Vincennes, Fort Knox II was abandoned and most of its wood was floated downstream for the construction of Fort Knox III (1813-1816) within the town. This fort stood on the ground once occupied by British Fort Sackville. The George Rogers Clark Memorial now stands on that ground as part of the George Rogers Clark National Historical Park.